Stockholders' Equity and EPS - QTD Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	$ 5,706,175	$ 4,804,841	$ 5,264,843	$ 4,319,415
Common stock issued under employee benefit plans, net of restricted stock cancellations	1,383	1,943	9,236	9,108
Net income	281,718	281,365	909,901	736,417
Capital calls and distributions, net	(8,780)	(8,060)	(32,002)	(22,785)
Net change in unrealized gains and losses on AFS securities, net of tax	50,638	(17,908)	173,235	(70,763)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(270)	(1,283)	(1,275)	(2,830)
Foreign currency translation adjustments, net of tax	(4,482)	(2,354)	(4,550)	(3,855)
Net change in unrealized gains and losses on cash flow hedges, net of tax	9,035		22,863
Share-based compensation, net	18,782	11,501	50,550	33,968
Common stock repurchases	(5,730)		(352,511)
Balance, end of period, net of tax	$ 6,048,469	$ 5,070,045	$ 6,048,469	$ 5,070,045
Common Stock
Stockholders Equity Note [Line Items]
Balance (in shares)	51,561,719	53,210,627	52,586,498	52,835,188
Balance, beginning of period, net of tax	$ 52	$ 53	$ 53	$ 53
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)	19,674	39,628	487,101	405,395
Common stock issued under employee benefit plans, net of restricted stock cancellations			$ 0	$ 0
Common stock repurchases (in shares)	(25,562)		(1,532,210)
Common stock repurchases	$ 0		$ (1)
Balance (in shares)	51,555,831	53,250,255	51,555,831	53,250,255
Balance, end of period, net of tax	$ 52	$ 53	$ 52	$ 53
Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	1,421,565	1,346,586	1,378,438	1,314,377
Common stock issued under employee benefit plans, net of restricted stock cancellations	1,383	1,943	9,236	9,108
Share-based compensation, net	18,782	11,501	50,550	33,968
Balance, end of period, net of tax	1,441,730	1,360,030	1,441,730	1,360,030
Retained Earnings
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	4,051,194	3,397,879	3,791,838	2,866,837
Net income	267,281	274,817	874,000	707,576
Common stock repurchases	(5,730)		(352,510)
Balance, end of period, net of tax	4,312,745	3,672,696	4,312,745	3,672,696
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	81,232	(86,865)	(54,120)	(1,472)
Net change in unrealized gains and losses on AFS securities, net of tax	50,638	(17,908)	173,235	(70,763)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(270)	(1,283)	(1,275)	(2,830)
Foreign currency translation adjustments, net of tax	(4,482)	(2,354)	(4,550)	(3,855)
Net change in unrealized gains and losses on cash flow hedges, net of tax	9,035		22,863
Balance, end of period, net of tax	136,153	(108,410)	136,153	(108,410)
Total SVBFG Stockholders’ Equity
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	5,554,043	4,657,653	5,116,209	4,179,795
Common stock issued under employee benefit plans, net of restricted stock cancellations	1,383	1,943	9,236	9,108
Net income	267,281	274,817	874,000	707,576
Net change in unrealized gains and losses on AFS securities, net of tax	50,638	(17,908)	173,235	(70,763)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(270)	(1,283)	(1,275)	(2,830)
Foreign currency translation adjustments, net of tax	(4,482)	(2,354)	(4,550)	(3,855)
Net change in unrealized gains and losses on cash flow hedges, net of tax	9,035		22,863
Share-based compensation, net	18,782	11,501	50,550	33,968
Common stock repurchases	(5,730)		(352,511)
Balance, end of period, net of tax	5,890,680	4,924,369	5,890,680	4,924,369
Noncontrolling Interests
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	152,132	147,188	148,634	139,620
Net income	14,437	6,548	35,901	28,841
Capital calls and distributions, net	(8,780)	(8,060)	(32,002)	(22,785)
Balance, end of period, net of tax	$ 157,789	$ 145,676	$ 157,789	$ 145,676