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v3.10.0.1

Segment Reporting (Schedule Of Operating Information, Segment) (Parenthetical) (Details) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Segment Reporting [Abstract] |  |  |
Net revenues accounted for by individual client, maximum percentage | 10.00% | 10.00% | 10.00%

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- Definition Net revenues accounted for by individual client, maximum percentage. + References No definition available. + Details
Name: | sf_NetRevenuesAccountedForByIndividualClientMaximumPercentage
Namespace Prefix: | sf_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_SegmentReportingAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration