Revenue, Carried Interest Allocation As Percentage Of Cumulative Fund Or Account Performance

No definition available.

Name:	step_RevenueCarriedInterestAllocationAsPercentageOfCumulativeFundOrAccountPerformance
Namespace Prefix:	step_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Revenue, Carried Interest Allocation, Minimum Return Levels Required

+ References

No definition available.

+ Details

Name:	step_RevenueCarriedInterestAllocationMinimumReturnLevelsRequired
Namespace Prefix:	step_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Revenue From Contract With Customer, Incentive Fees As Percentage Of Net Investment Income

+ References

No definition available.

+ Details

Name:	step_RevenueFromContractWithCustomerIncentiveFeesAsPercentageOfNetInvestmentIncome
Namespace Prefix:	step_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_AccountingPoliciesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8672-108599

+ Details

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

Name:	us-gaap_OperatingLeaseLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

Name:	us-gaap_OperatingLeaseRightOfUseAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands	3 Months Ended
	Jun. 30, 2021 USD ($) segment	Apr. 01, 2021 USD ($)	Mar. 31, 2021 USD ($)
Accounting Policies [Abstract]
Incentive fees as percentage of profits	10.00%
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease right-of-use assets, net \| $	$ 64,707	$ 66,700	$ 0
Lease liabilities \| $	$ 75,512	$ 76,900	$ 0
Number of operating segments \| segment	1
Number of reportable segments \| segment	1
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Carried interest allocation as percentage of cumulative fund or account performance	5.00%
Revenue, carried interest allocation, minimum return levels required	5.00%
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Carried interest allocation as percentage of cumulative fund or account performance	15.00%
Revenue, carried interest allocation, minimum return levels required	10.00%