Less: Accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Investments Investment, Policy [Policy Text Block] Net realized gains on investments Realized Investment Gains (Losses) Non-Controlling Interests in Legacy Greenspring Entities Legacy Entities [Member] Legacy Entities Award Timing Predetermined Award Timing Predetermined [Flag] Entity File Number Entity File Number Additional Paid-in Capital Additional Paid-in Capital [Member] O 2026 Q1 Dividends O 2026 Q1 Dividends [Member] O 2026 Q1 Dividends Tabular List, Table Tabular List [Table Text Block] Total compensation and benefits Compensation And Benefits Expense Compensation And Benefits Expense Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] AUD Screen Rate Multiplied By Statutory Reserve Rate AUD Screen Rate Multiplied By Statutory Reserve Rate [Member] AUD Screen Rate Multiplied By Statutory Reserve Rate Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Discount rate Liability Classified Awards, Discount Rate Liability Classified Awards, Discount Rate Secured Overnight Financing Rate (SOFR) Secured Overnight Financing Rate (SOFR) [Member] Debt securities Debt Securities [Member] Adjustment to Compensation: Adjustment to Compensation [Axis] Related Party Transactions Related Party Transactions Disclosure [Text Block] Unrealized Unrealized performance fee-related compensation Performance Fee-Related Compensation Related to Carried Interest Allocation, Unrealized Performance Fee-Related Compensation Related to Carried Interest Allocation, Unrealized Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Revenues Revenue from Contract with Customer [Text Block] Increase in deferred tax asset Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-Based Compensation Cost Exchange Two Exchange Two [Member] Exchange Two Shares purchased (in shares) Class A common stock issued under ESPP (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Total current income tax expense Current Income Tax Expense (Benefit) Class D exchange agreement, acceleration exchange, period Transaction Agreement, Maximum Period To Exchange Shares In Acceleration Exchange Transaction Agreement, Maximum Period To Exchange Shares In Acceleration Exchange Adjustment to Compensation, Amount Adjustment to Compensation Amount Equity method investment, total accrued carried interest allocation percentage Concentration Risk, Percentage Number of classes of common stock outstanding Number Of Classes Of Common Stock Outstanding Number Of Classes Of Common Stock Outstanding Other assets and receivables Other assets and receivables Increase (Decrease) in Other Operating Assets Consolidation Consolidation, Policy [Policy Text Block] Equity-based compensation Share-Based Payment Arrangement, Noncash Expense Employee Stock Option Share-Based Payment Arrangement, Option [Member] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Cash, Cash Equivalents and Restricted Cash Cash and Cash Equivalents, Policy [Policy Text Block] Taxes paid Income Taxes Paid Percent Effective Income Tax Rate Reconciliation, Percent [Abstract] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Dividends declared Dividends, Common Stock, Cash Total StepStone Group Inc. stockholders’ equity Equity, Attributable to Parent Insider Trading Policies and Procedures [Line Items] Class B Partnership Unit Class B Partnership Unit [Member] Class B Partnership Unit New York City NEW YORK Schedule of Property and equipment Property, Plant and Equipment [Table Text Block] Common stock, shares authorized (in shares) Common Stock, Shares Authorized S 2026 Q1 Dividends S 2026 Q1 Dividends [Member] S 2026 Q1 Dividends Interest rate in effect Line of Credit Facility, Interest Rate at Period End Concentrations of Risk Concentration Risk, Credit Risk, Policy [Policy Text Block] Liabilities and stockholders’ equity Liabilities and Equity [Abstract] U.S. state and local State and Local Jurisdiction [Member] Due to affiliates Accounts Payable, Other Cover [Abstract] Maximum Maximum [Member] Net cash recognized upon initial consolidation of funds Net Cash Recognized Upon Initial Consolidation of Consolidated Funds Net Cash Recognized Upon Initial Consolidation of Consolidated Funds Finite-lived intangible assets, estimated useful lives Finite-Lived Intangible Asset, Useful Life Less: Net income attributable to non-controlling interests Net Income (Loss) Attributable to Noncontrolling Interest Intangible assets, net Finite-Lived Intangible Assets, Net Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Changes in unrealized gains included in earnings related to financial liabilities still held at the reporting date Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss) Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Carried interest allocations, SMAs Carried Interest Allocation, Separately Managed Accounts [Member] Carried Interest Allocation, Separately Managed Accounts Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Retirement Benefits [Abstract] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Temporary Equity [Line Items] Temporary Equity [Line Items] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income (loss) before income tax Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Accounts payable, accrued expenses and other liabilities Accounts Payable and Other Accrued Liabilities Schedule of Long-Term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Proceeds from issuance of notes payable Proceeds from Issuance of Debt Schedule of Cash Paid for Income Taxes Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Line of Credit Facility [Table] Line of Credit Facility [Table] Advisory and other services Management And Advisory Fees, Net, Advisory And Other Services [Member] Management And Advisory Fees, Net, Advisory And Other Services Vesting of Class B2 units and issuance of corresponding Class B common stock at par value Stock Issued During Period, Value, Restricted Stock Award, Net of Shares Withheld For Employee Taxes Stock Issued During Period, Value, Restricted Stock Award, Net of Shares Withheld For Employee Taxes Letters of credit Letter of Credit [Member] Purchase of non-controlling interests Payments to Noncontrolling Interests Non-Controlling Interests in the Partnership Partnership Of Subsidiary [Member] Partnership Of Subsidiary Domestic income (loss) before income tax Income (Loss) from Continuing Operations before Income Taxes, Domestic Swiss Average Rate Overnight Swiss Average Rate Overnight [Member] Swiss Average Rate Overnight Due from affiliates Due from affiliates, net Other Receivables Purchases of investments of Consolidated Funds Investments Of Consolidated Funds, Cost Investments Of Consolidated Funds, Cost Document Fiscal Period Focus Document Fiscal Period Focus Award Timing Method Award Timing Method [Text Block] Class D Partnership Units Class D Partnership Units [Member] Class D Partnership Units Office furniture Furniture and Fixtures [Member] Award Type [Axis] Award Type [Axis] Realized Performance Fee-Related Compensation Related to Carried Interest Allocation, Realized Performance Fee-Related Compensation Related to Carried Interest Allocation, Realized Deconsolidation of fund - Level III derecognition Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Deconsolidation Of Fund Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Deconsolidation Of Fund Foreign currency translation adjustments Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Valuation Allowance [Roll Forward] Valuation Allowance [Roll Forward] Valuation Allowance Additional note payable available to be issued by consolidated funds Long Term Debt, Available To Be Issued By Consolidated Funds Long Term Debt, Available To Be Issued By Consolidated Funds Carried interest, contingent repayment obligations Equity Method Investment, Carried Interest Allocations, Maximum Amount Subject To Contingent Repayment Equity Method Investment, Carried Interest Allocations, Maximum Amount Subject To Contingent Repayment Investment, Name [Domain] Investment, Name [Domain] Trading Symbol Trading Symbol FY2030 Lessee, Operating Lease, Liability, to be Paid, Year Four Legacy carried interest allocation as percentage of cumulative fund or account performance Revenue, Legacy Carried Interest Allocation As Percentage Of Cumulative Fund Or Account Performance Revenue, Legacy Carried Interest Allocation As Percentage Of Cumulative Fund Or Account Performance Changes in valuation allowances Valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Class A common stock issued for vesting of equity-based awards, net of shares withheld for taxes (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Entity Address, City or Town Entity Address, City or Town Variable Interest Entity, Not Primary Beneficiary, Subsidiaries Variable Interest Entity, Not Primary Beneficiary, Subsidiaries [Member] Variable Interest Entity, Not Primary Beneficiary, Subsidiaries SMAs Management And Advisory Fees, Net, Separately Managed Accounts [Member] Management And Advisory Fees, Net, Separately Managed Accounts Effect of foreign currency exchange rate changes Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Total net deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Entity Emerging Growth Company Entity Emerging Growth Company Class A common stock issued for purchase of asset class non-controlling interests (in shares) Stockholders' Equity, Units Issued For Purchase Of Asset Class Noncontrolling Interest Stockholders' Equity, Units Issued For Purchase Of Asset Class Noncontrolling Interest Other Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount [Abstract] Payments on fund credit facility Repayments of Lines of Credit Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Less: Debt issuance costs Debt Issuance Costs, Net SRA SRA [Member] SRA Borrowings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases Class B2 Interests Class B2 Interests [Member] Class B2 Interests Class C common stock Common Class C [Member] Common stock, shares outstanding (in shares) Common stock, shares outstanding, beginning balance (in shares) Common stock, shares outstanding, ending balance (in shares) Common Stock, Shares, Outstanding Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Number of investment funds consolidated Number Of Consolidated Investment Funds Number Of Consolidated Investment Funds Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Increase in valuation allowance Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Cash-based incentive awards, expense Deferred Compensation Arrangement with Individual, Compensation Expense Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Schedule of Product Information [Table] Nature of Operation, Product Information, Concentration of Risk [Table] Schedule of Future Amortization of Finite-lived Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Legacy Greenspring Carried Interest Allocations Legacy Carried Interest Allocation [Member] Legacy Carried Interest Allocation Number of RSUs and PRSU Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Income tax expense (benefit) Income tax expense Total income tax expense (benefit) Income Tax Expense (Benefit) Basis spread on variable interest rate Debt Instrument, Basis Spread on Variable Rate Class B Common Stock Class B common stock, $0.001 par value, 125,000,000 authorized; 38,637,761 and 39,656,954 issued and outstanding as of March 31, 2026 and 2025, respectively Class B Common Stock Common Class B [Member] New York Federal Reserve Bank Rate New York Federal Reserve Bank Rate [Member] New York Federal Reserve Bank Rate Other assets and receivables Other Assets Balance, beginning of period: Balance, end of period: Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Preferred stock, issued (in shares) Preferred Stock, Shares Issued Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Due to related parties, tax receivable agreements Due To Related Parties, Tax Receivable Agreements Due To Related Parties, Tax Receivable Agreements Property and equipment, gross Property, Plant and Equipment, Gross Legacy carried interest allocation, SMAs Legacy Carried Interest Allocation, Separately Managed Accounts [Member] Legacy Carried Interest Allocation, Separately Managed Accounts Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] U.S. federal Income Tax Paid, Federal, after Refund Received All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Redemption price, percentage Debt Instrument, Redemption Price, Percentage Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Beginning balance (in shares) Beginning balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Summary of Class A Common Stock Repurchased Schedule Of Stock Repurchase [Table Text Block] Schedule Of Stock Repurchase Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Debt instrument, term Debt Instrument, Term Equity Method Investments and Joint Ventures [Abstract] Shares exchanged (in shares) Stockholders' Equity, Share Exchange, Shares Exchanged Stockholders' Equity, Share Exchange, Shares Exchanged Liquidity Loan Facility Liquidity Loan Facility [Member] Liquidity Loan Facility Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Property and equipment, estimated useful lives Property, Plant and Equipment, Useful Life Subsequent Event Subsequent Event [Member] Equity method investments Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Foreign Income Tax Paid, Foreign, after Refund Received [Abstract] Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Depreciation Depreciation Investments of consolidated funds, percent of total investments Investments of Consolidated Funds, Percent Of Total Investments Investments of Consolidated Funds, Percent Of Total Investments Numerator: Net Income (Loss) Available to Common Stockholders, Diluted [Abstract] Equity Components [Axis] Equity Components [Axis] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Sublease income Sublease Income Shares issued (in shares) Stockholders' Equity, Share Exchange, Shares Issued Stockholders' Equity, Share Exchange, Shares Issued Class Of Partnership Unit [Axis] Class Of Partnership Unit [Axis] Class Of Partnership Unit Unrealized investment income of Consolidated Funds Unrealized Investment Gain (Loss) From Consolidated Funds Unrealized Investment Gain (Loss) From Consolidated Funds Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Number of reportable segments Number of Reportable Segments Excluding Consolidated Funds Excluding Consolidated Funds [Member] Excluding Consolidated Funds Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Entity Address, State or Province Entity Address, State or Province Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Security, Excluded EPS Calculation [Table] Individual: Individual [Axis] Non-discretionary contributions Defined Contribution Plan, Cost Income Tax Jurisdiction [Domain] Income Tax Jurisdiction [Domain] Dividends paid to common stockholders Payments of Ordinary Dividends, Common Stock Document Annual Report Document Annual Report Entities [Table] Entities [Table] Proceeds from sale of non-controlling interests Contributions from redeemable non-controlling interests in Consolidated Funds Proceeds from Noncontrolling Interests Maximum exposure to loss Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Less: Comprehensive income attributable to redeemable non-controlling interests Comprehensive Income (Loss), Net Of Tax, Redeemable Noncontrolling Interest Comprehensive Income (Loss), Net Of Tax, Redeemable Noncontrolling Interest Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Entity Interactive Data Current Entity Interactive Data Current Contributed capital Partners' Capital Account, Contributions Underfunded pension obligation Defined Benefit Plan, Funded (Unfunded) Status of Plan Amounts receivable from loans Other Receivables, Loans [Member] Other Receivables, Loans Minimum amount of prepayment, percentage Debt Instrument, Minimum Amount Of Prepayment, Percentage Debt Instrument, Minimum Amount Of Prepayment, Percentage Carried interest allocation, focused commingled funds Carried Interest Allocation, Focused Commingled Funds [Member] Carried Interest Allocation, Focused Commingled Funds Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Axis] Partnership StepStone Group LP [Member] StepStone Group LP Ownership [Domain] Ownership [Domain] Legacy carried interest allocation, focused comingled funds Legacy Carried Interest Allocation, Focused Commingled Funds [Member] Legacy Carried Interest Allocation, Focused Commingled Funds Entity Central Index Key Entity Central Index Key Noncontrolling Interest in Consolidated Funds Noncontrolling Interest In Consolidated Funds [Member] Noncontrolling Interest In Consolidated Funds PEO Name PEO Name Total revenues Revenues Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] LTIP 2020 Long-Term Incentive Plan [Member] 2020 Long-Term Incentive Plan Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Balance, beginning of period: Balance, end of period: Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value Share-based Payment Arrangement, Tranche One Share-Based Payment Arrangement, Tranche One [Member] Amounts payable to non-controlling interest holders in connection with Tax Receivable Agreements Other Liabilities, Non-Controlling Interest Holders due to Tax Receivable Agreements [Member] Other Liabilities, Non-Controlling Interest Holders due to Tax Receivable Agreements SRE SRE [Member] SRE Exercise Price Award Exercise Price Share exchange ratio Stockholder's Equity, Share Exchange Ratio Stockholder's Equity, Share Exchange Ratio Entity Filer Category Entity Filer Category Class of Stock [Domain] Class of Stock [Domain] U.S. federal statutory income tax rate Federal tax at statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Subsequent Event Type [Axis] Subsequent Event Type [Axis] Changes in operating assets and liabilities of Consolidated Funds: Adjustments To Reconcile Net Income (Loss) To Cash Provided By (Used In) Operating Activities, Consolidated Funds [Abstract] Adjustments To Reconcile Net Income (Loss) To Cash Provided By (Used In) Operating Activities, Consolidated Funds Focused commingled funds Management And Advisory Fees, Net, Focused Commingled Funds [Member] Management And Advisory Fees, Net, Focused Commingled Funds Less: Comprehensive income (loss) attributable to non-controlling interests Comprehensive Income (Loss), Net of Tax, Attributable to Nonredeemable Noncontrolling Interest Comprehensive Income (Loss), Net of Tax, Attributable to Nonredeemable Noncontrolling Interest 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Three Vesting [Domain] Vesting [Domain] Decrease in deferred tax assets, Transaction Agreements Increase (Decrease) in Deferred Tax Asset, Transaction Agreements Increase (Decrease) in Deferred Tax Asset, Transaction Agreements Deferred tax assets: Deferred Tax Assets, Net [Abstract] Intangible assets, gross Finite-Lived Intangible Assets, Gross Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Entity Address, Address Line One Entity Address, Address Line One Accumulated Other Comprehensive Income Accumulated other comprehensive income AOCI Attributable to Parent [Member] Investments [Domain] Investments [Domain] Redeemable non-controlling interests in Consolidated Funds Beginning balance Ending balance Redeemable Noncontrolling Interest, Equity, Carrying Amount Ownership [Axis] Ownership [Axis] Schedule of Rollforward of the Company's Shares of Common Stock Outstanding Since IPO Schedule of Stock by Class [Table Text Block] Legacy Greenspring investments in funds Legacy Investments In Funds Legacy Investments In Funds Fair Value as of Grant Date Award Grant Date Fair Value Computer equipment and software Computer Equipment And Software [Member] Computer Equipment And Software Total Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Assumed vesting of shares (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Maximum share purchase, value Share-Based Compensation Arrangement by Share-Based Payment Award, Maximum Number of Shares Per Employee, Value Share-Based Compensation Arrangement by Share-Based Payment Award, Maximum Number of Shares Per Employee, Value Total expenses Expenses Costs and Expenses Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unrecognized non-cash compensation Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Related Party Transaction [Line Items] Related Party Transaction [Line Items] Adjustments to reconcile net income (loss) to net cash used in operating activities of Consolidated Funds: Adjustments To Reconcile Net Income (Loss) To Net Cash Provided By Operating Activities Of Consolidated Funds [Abstract] Adjustments To Reconcile Net Income (Loss) To Net Cash Provided By Operating Activities Of Consolidated Funds Change in deferred income taxes Deferred Income Taxes and Tax Credits Debt obligations of Consolidated Funds Long-Term Debt, Fair Value Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Amounts payable to StepStone Funds Other Liabilities, StepStone Funds [Member] Other Liabilities, StepStone Funds Counterparty Name [Domain] Counterparty Name [Domain] FY2028 Lessee, Operating Lease, Liability, to be Paid, Year Two Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Sterling Overnight Index Average Sterling Overnight Index Average [Member] Sterling Overnight Index Average Investment Type [Axis] Investment Type [Axis] Investments, at fair value Investments Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Non-PEO NEO Non-PEO NEO [Member] Letters of credit outstanding Letters of Credit Outstanding, Amount Class A common stock issued under ESPP Stock Issued During Period, Value, Employee Stock Purchase Plan Lease term Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Sale of Stock [Axis] Sale of Stock [Axis] GBP Base Rate GBP Base Rate [Member] GBP Base Rate Award Type [Domain] Award Type [Domain] FY2027 Lessee, Operating Lease, Liability, to be Paid, Year One Class D exchange agreement, period Transaction Agreement, Maximum Period To Exchange Shares Transaction Agreement, Maximum Period To Exchange Shares Incremental income from assumed vesting of units Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units Non-controlling interests Less: Amounts attributable to non-controlling interests Equity, Attributable to Noncontrolling Interest Equity Awards Adjustments Equity Awards Adjustments [Member] Leasehold improvements Leasehold Improvements [Member] Other non-cash activities Other Noncash Income (Expense) Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Effects of cross-border tax laws Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Percent Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Investments in funds Investments in funds Equity Method Investments, Excluding Accrued Carried Interest Allocations Equity Method Investments, Excluding Accrued Carried Interest Allocations Compensation Amount Outstanding Recovery Compensation Amount Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Switzerland SWITZERLAND Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Deferred revenue, revenue recognized Contract with Customer, Liability, Revenue Recognized Accrued compensation and benefits Increase (Decrease) in Employee Related Liabilities MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Other Foreign taxes Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Australia AUSTRALIA Fair value adjustment for acquisition-related contingent consideration Business Combination, Contingent Consideration, Change in Contingent Consideration, Liability, Increase (Decrease) Weighted-average shares of Class A common stock: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Employee Stock Employee Stock [Member] Revenues Revenues [Abstract] Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Total deferred tax liabilities Deferred Tax Liabilities, Gross Net cash derecognized from deconsolidation of fund Cash Divested from Deconsolidation Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Base interest rate Debt Instrument, Base Interest Rate Debt Instrument, Base Interest Rate Other Effective Income Tax Rate Reconciliation, Other Reconciling Items, Percent [Abstract] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Minimum Minimum [Member] Company Selected Measure Name Company Selected Measure Name Debt Obligations Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Operating cash flows used for operating leases Operating Lease, Payments Membership ownership percentage Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Total performance fee-related compensation Performance Fee-Related Compensation Related to Carried Interest Allocation Performance Fee-Related Compensation Related to Carried Interest Allocation Net income (loss) attributable to StepStone Group Inc. – Diluted Net Income (Loss) Available to Common Stockholders, Diluted Foreign Current Foreign Tax Expense (Benefit) Legacy Greenspring accrued carried interest allocations Legacy Accrued Carried Interest Allocations Legacy Accrued Carried Interest Allocations Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Share-based Payment Arrangement, Tranche Two Share-Based Payment Arrangement, Tranche Two [Member] Diluted (in shares) Weighted-average shares of Class A common stock outstanding - Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Total equity method income Revenue Not From Contract With Customer, Income Loss From Equity Method Investments And Investment Income Revenue Not From Contract With Customer, Income Loss From Equity Method Investments And Investment Income Segments Segment Reporting, Policy [Policy Text Block] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Number of separately managed accounts greater than or equal to 10% of incentive fees Separately Managed Accounts, Greater Than Or Equal To 10% Of Incentive Fees Separately Managed Accounts, Greater Than Or Equal To 10% Of Incentive Fees Entity Small Business Entity Small Business Income Tax Disclosure [Abstract] Less: Net income attributable to redeemable non-controlling interests Net income Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Schedule of Subsidiary of Limited Liability Company or Limited Partnership [Table] Subsidiary of LLC or LP [Table] Preferred stock, outstanding (in shares) Preferred Stock, Shares Outstanding State and local Current State and Local Tax Expense (Benefit) Document Transition Report Document Transition Report Underlying Securities Award Underlying Securities Amount Equity Component [Domain] Equity Component [Domain] Statement of Partners' Capital [Abstract] Document Period End Date Document Period End Date Redemption of redeemable non-controlling interests Temporary Equity, Accretion to Redemption Value Income Taxes Income Tax Disclosure [Text Block] Limited Partners Limited Partners [Member] Limited Partners Proceeds from borrowings on fund credit facility Proceeds from Lines of Credit Class A Common Stock Class A common stock, $0.001 par value, 650,000,000 authorized; 80,703,553 and 76,761,399 issued and outstanding as of March 31, 2026 and 2025, respectively Class A Common Stock Common Class A [Member] Payments for acquisition-related contingent consideration Payment for Contingent Consideration Liability, Financing Activities Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Total stockholders’ equity Total stockholders' equity, beginning balance Total stockholders' equity, ending balance Equity Equity, Including Portion Attributable to Noncontrolling Interest Average price paid per share Shares Acquired, Average Cost Per Share Document Type Document Type Level III Fair Value, Inputs, Level 3 [Member] Current Events Current Events, Policy [Policy Text Block] Current Events, Policy Earnings Per Share Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Additional paid-in capital Additional Paid in Capital Product and Service [Axis] Product and Service [Axis] S 2024 Q1 Dividends S 2024 Q1 Dividends [Member] S 2024 Q1 Dividends Fund investments Fund Investments [Member] Fund Investments Variable lease cost Variable Lease, Cost Revenues Service fees Revenue from Contract with Customer, Excluding Assessed Tax Common Class D Common Class D [Member] Common Class D Statistical Measurement [Axis] Statistical Measurement [Axis] Share repurchase program, authorized, amount Share Repurchase Program, Authorized, Amount Unused commitment fee percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Payments for taxes related to net settlement of equity-based awards Payment, Tax Withholding, Share-Based Payment Arrangement Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Entity Information [Line Items] Entity Information [Line Items] Level I Fair Value, Inputs, Level 1 [Member] Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Table] Diluted (in dollars per share) Diluted (in dollars per share) Earnings Per Share, Diluted Tax Receivable Agreements Tax Receivable Agreement, Policy [Policy Text Block] Tax Receivable Agreement, Policy Dividends [Axis] Dividends [Axis] U.S. state and local Income Tax Paid, State and Local, after Refund Received Auditor Location Auditor Location Variable Interest Entity, Not Primary Beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] Investments Equity Method Investments and Joint Ventures Disclosure [Text Block] Repurchases of Class A common stock Total cost Stock Repurchased and Retired During Period, Value Consolidated Funds Consolidated Funds [Member] Consolidated Funds Accumulated Other Comprehensive Income Comprehensive Income, Policy [Policy Text Block] Less: Imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Series A 5.52% Notes Series A 5.52% Notes [Member] Series A 5.52% Notes Total cash paid for income taxes, net of refunds Income Taxes Paid, Net 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Two Total remaining principal Long-Term Debt, Gross Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Property and Equipment Property, Plant and Equipment Disclosure [Text Block] Total lease liabilities Lessee, Operating Lease, Liability, to be Paid Non-Controlling Interests in Subsidiaries Subsidiaries [Member] S 2025 Q1 Dividends S 2025 Q1 Dividends [Member] S 2025 Q1 Dividends Distributions Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Income passed through to limited partners Effective Income Tax Rate Reconciliation, Income Passed Through To Limited Partners, Percent Effective Income Tax Rate Reconciliation, Income Passed Through To Limited Partners, Percent Dividends [Domain] Dividends [Domain] Expiration Date Trading Arrangement Expiration Date Other liabilities and payables Increase (Decrease) in Other Operating Liabilities Amounts allocated to non-controlling interests Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent 2031 Finite-Lived Intangible Asset, Expected Amortization, Year Five Product Information [Line Items] 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