Parent Company Only Condensed Financial Information - Condensed Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Condensed Statement of Income Captions [Line Items]
Net income available to common stockholders	$ 266,264	$ 274,817	$ 237,798	$ 194,961	$ 117,210	$ 148,620	$ 123,193	$ 101,483	$ 973,840	[1]	$ 490,506	[1]	$ 382,685
Other comprehensive income (loss), net of tax									(52,648)		(24,902)		8,026
Comprehensive income attributable to SVBFG									921,192		465,604		390,711
Parent Company
Condensed Statement of Income Captions [Line Items]
Net income available to common stockholders									973,840		490,506		382,685
Foreign currency translation gains (losses)									(4,107)		3,769		3,071
Unrealized holding gains (losses) on securities available for sale									120		22,285		654
Equity in other comprehensive income (losses) of subsidiaries									(19,171)		(50,956)		4,301
Reclassifications due to new accounting guidance									(29,490)		0		0
Other comprehensive income (loss), net of tax									(52,648)		(24,902)		8,026
Comprehensive income attributable to SVBFG									$ 921,192		$ 465,604		$ 390,711

[1] Included in income tax expense, net income available to common stockholders, earnings per common share-basic and earnings for common share-diluted, for the years ended December 31, 2018 and 2017, are tax benefits recognized associated with the adoption of Accounting Standards Update ("ASU") 2016-09, Improvements to Employee Share-Based Payment Accounting in the first quarter of 2017. This guidance was adopted on a prospective basis with no change to prior period amounts.