Interim Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 561,764	$ 133,649
Change in foreign currency cumulative translation gains and losses:
Foreign currency translation losses	(43)	(9,120)
Related tax benefit	13	2,556
Change in unrealized gains and losses on available-for-sale securities:
Unrealized holding (losses) gains	(823,329)	543,881
Related tax benefit (expense)	228,876	(150,746)
Reclassification adjustment for gains included in net income	0	(61,165)
Related tax expense	0	16,953
Cumulative-effect adjustment for unrealized gains on securities transferred from available-for-sale to held-to-maturity	8,710	0
Related tax expense	(2,421)	0
Amortization of unrealized holding losses on securities transferred from available-for-sale to held-to-maturity	(2,851)	(552)
Related tax benefit	793	153
Change in unrealized gains and losses on cash flow hedges:
Unrealized gains	0	231,920
Related tax expense	0	(64,281)
Reclassification adjustment for gains included in net income	(15,657)	(2,089)
Related tax expense	4,352	579
Other comprehensive (loss) income, net of tax	(601,557)	508,089
Comprehensive (loss) income	(39,793)	641,738
Comprehensive (income) loss attributable to noncontrolling interests	(24,950)	1,973
Comprehensive (loss) income attributable to SVBFG	$ (64,743)	$ 643,711