Employee Compensation and Benefit Plans Expenses Incurred Under Certain Employee Compensation and Benefit Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Benefits Disclosure [Line Items]
Incentive Compensation Plans	$ 125,584	$ 96,892	$ 97,565
Direct Drive Incentive Compensation Plan	18,721	21,174	21,930
Retention Program	1,317	1,475	1,996
Warrant Incentive Plan	15,386	4,954	9,110
Deferred Compensation Arrangement with Individual, Compensation Expense	203	1,318	2,404
SVBFG 401(k) Plan	17,860	16,078	13,809
SVBFG Employee Stock Ownership Plan	$ 4,719	$ 3,159	$ 8,585