Capital raising and advisory fee revenues.

No definition available.

Name:	sf_CapitalRaisingAndAdvisoryFeeRevenues
Namespace Prefix:	sf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Increase (decrease) in net cash provided by operating activities.

+ References

No definition available.

+ Details

Name:	sf_IncreaseDecreaseInNetCashProvidedByOperatingActivities
Namespace Prefix:	sf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of the cumulative effect on retained earnings net of related income tax effect.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794

+ Details

Name:	us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

+ References

No definition available.

+ Details

Name:	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

The total amount of other operating cost and expense items that are associated with the entity's normal revenue producing operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

Name:	us-gaap_OtherCostAndExpenseOperating
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=sf_AccountingStandardsUpdate201802Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201618Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201409Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

New Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Other operating expenses	$ 81,885	$ 85,257	$ 154,337	$ 148,270
ASU 2018-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification adjustment related to cash flow hedges and investment portfolio credit risk			3,000
ASU 2016-18 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Decrease in net cash provided by operating activities			73,100
ASU 2014-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect on retained earnings			3,900
Capital raising and advisory fee revenues	16,200		$ 16,200
Other operating expenses	$ 16,200