Parent Company Only Condensed Financial Information - Condensed Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Statement of Income Captions [Line Items]
Net income available to common stockholders	$ 262,856	$ 267,281	$ 317,987	$ 288,732	$ 266,264	$ 274,817	$ 237,798	$ 194,961	$ 1,136,856	$ 973,840	$ 490,506
Other comprehensive income (loss), net of tax									138,565	(52,648)	(24,902)
Comprehensive income attributable to SVBFG									1,275,421	921,192	465,604
Parent Company
Condensed Statement of Income Captions [Line Items]
Net income available to common stockholders									1,136,856	973,840	490,506
Foreign currency translation gains (losses)									2,319	(4,107)	3,769
Changes in fair value on cash flow hedges									(2,130)	0	0
Changes in unrealized holding gains and losses on AFS securities									2,310	120	22,285
Equity in other comprehensive income (loss) of bank and nonbank subsidiaries									136,066	(19,171)	(50,956)
Reclassifications to retained earnings for the adoption of new accounting guidance									0	(29,490)	0
Other comprehensive income (loss), net of tax									138,565	(52,648)	(24,902)
Comprehensive income attributable to SVBFG									$ 1,275,421	$ 921,192	$ 465,604