Interim Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Series B Preferred Stock	Cumulative adjustment for the adoption of amendment	Preferred Stock	Preferred Stock Series B Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative adjustment for the adoption of amendment	Accumulated Other Comprehensive Income (Loss)	Total SVBFG Stockholders’ Equity	Total SVBFG Stockholders’ Equity Series B Preferred Stock	Total SVBFG Stockholders’ Equity Cumulative adjustment for the adoption of amendment	Noncontrolling Interests
Balance (in shares) at Dec. 31, 2019						51,655,607,000
Balance, beginning of period, net of tax at Dec. 31, 2019	$ 6,621,080			$ 340,138		$ 52	$ 1,470,071	$ 4,575,601		$ 84,445	$ 6,470,307			$ 150,773
Balance, beginning of period, net of tax (Accounting Standards Update 2017-08) at Dec. 31, 2019			$ (35,049)						$ (35,049)				$ (35,049)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)						66,864,000
Common stock issued under employee benefit plans, net of restricted stock cancellations	(3,031)					$ 0	(3,031)				(3,031)
Common stock issued under ESOP (in shares)						12,094,000
Common stock issued under ESOP	2,447						2,447				2,447
Net income	133,649							135,622			135,622			(1,973)
Capital calls and distributions, net	(328)													(328)
Net change in unrealized gains and losses on AFS securities, net of tax	348,923									348,923	348,923
Amortization of unrealized holding gains and losses on securities transferred from AFS to HTM, net of tax	(399)									(399)	(399)
Foreign currency translation adjustments, net of tax	(6,564)									(6,564)	(6,564)
Net change in unrealized gains and losses on cash flow hedges, net of tax	166,129									166,129	166,129
Share-based compensation, net	19,171						19,171				19,171
Common stock repurchases (in shares)						(244,223,000)
Common stock repurchases	(60,020)					$ 0		(60,020)			(60,020)
Dividends on preferred stock	(3,369)							(3,369)			(3,369)
Other	582						582				582
Balance (in shares) at Mar. 31, 2020						51,490,342,000
Balance, end of period, net of tax at Mar. 31, 2020	7,183,221			340,138		$ 52	1,489,240	4,612,785		592,534	7,034,749			148,472
Balance (in shares) at Dec. 31, 2020						51,888,463,000
Balance, beginning of period, net of tax at Dec. 31, 2020	8,433,491			340,138		$ 52	1,585,244	5,671,749		622,517	8,219,700			213,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)						107,234,000
Common stock issued under employee benefit plans, net of restricted stock cancellations	(1,421)					$ 0	(1,421)				(1,421)
Common stock issued under ESOP (in shares)						6,100,000
Common stock issued under ESOP	3,138						3,138				3,138
Issuance of stock	972,115	$ 739,195				$ 2	972,113				972,115	$ 739,195
Issuance of stock (in shares)					739,195,000	2,000,000,000
Net income	561,764							536,814			536,814			24,950
Capital calls and distributions, net	(12,854)													(12,854)
Net change in unrealized gains and losses on AFS securities, net of tax	(594,453)									(594,453)	(594,453)
Amortization of unrealized holding gains and losses on securities transferred from AFS to HTM, net of tax	4,231									4,231	4,231
Foreign currency translation adjustments, net of tax	(30)									(30)	(30)
Net change in unrealized gains and losses on cash flow hedges, net of tax	(11,305)									(11,305)	(11,305)
Share-based compensation, net	26,691						26,691				26,691
Dividends on preferred stock	(4,594)							(4,594)			(4,594)
Other	4,811						4,811				4,811
Balance (in shares) at Mar. 31, 2021						54,001,797,000
Balance, end of period, net of tax at Mar. 31, 2021	$ 10,120,779			$ 1,079,333		$ 54	$ 2,590,576	$ 6,203,969		$ 20,960	$ 9,894,892			$ 225,887