Stockholders' Equity and EPS - QTD Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stockholders Equity Note [Line Items]
Beginning balance	$ 5,483,823	$ 4,559,724	$ 5,264,843	$ 4,319,415
Common stock issued under employee benefit plans, net of restricted stock cancellations	10,789	7,644	7,853	7,165
Net income	336,571	247,026	628,183	455,052
Capital calls and distributions, net	(7,502)	(6,318)	(23,222)	(14,725)
Net change in unrealized gains and losses on AFS securities, net of tax	86,186	(10,754)	122,597	(52,855)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(519)	(674)	(1,005)	(1,547)
Foreign currency translation adjustments, net of tax	(2,092)	(3,751)	(68)	(1,501)
Net change in unrealized gains and losses on cash flow hedges, net of tax	13,031		13,828
Share-based compensation, net	16,646	11,944	31,768	22,467
Common stock repurchases	(230,758)		(346,781)
Ending balance	$ 5,706,175	$ 4,804,841	$ 5,706,175	$ 4,804,841
Common Stock
Stockholders Equity Note [Line Items]
Balance (in shares)	52,322,105	52,922,219	52,586,498	52,835,188
Beginning balance	$ 52	$ 53	$ 53	$ 53
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)	257,684	288,408	467,427	365,767
Common stock issued under employee benefit plans, net of restricted stock cancellations			$ 0	$ 0
Common stock repurchases (in shares)	(1,018,070)		(1,506,648)
Common stock repurchases	$ 0		$ (1)
Balance (in shares)	51,561,719	53,210,627	51,561,719	53,210,627
Ending balance	$ 52	$ 53	$ 52	$ 53
Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Beginning balance	1,394,130	1,326,998	1,378,438	1,314,377
Common stock issued under employee benefit plans, net of restricted stock cancellations	10,789	7,644	7,853	7,165
Share-based compensation, net	16,646	11,944	31,768	22,467
Ending balance	1,421,565	1,346,586	1,421,565	1,346,586
Retained Earnings
Stockholders Equity Note [Line Items]
Beginning balance	3,963,965	3,160,081	3,791,838	2,866,837
Net income	317,987	237,798	606,719	432,759
Common stock repurchases	(230,758)		(346,780)
Ending balance	4,051,194	3,397,879	4,051,194	3,397,879
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Beginning balance	(15,374)	(71,686)	(54,120)	(1,472)
Net change in unrealized gains and losses on AFS securities, net of tax	86,186	(10,754)	122,597	(52,855)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(519)	(674)	(1,005)	(1,547)
Foreign currency translation adjustments, net of tax	(2,092)	(3,751)	(68)	(1,501)
Net change in unrealized gains and losses on cash flow hedges, net of tax	13,031		13,828
Ending balance	81,232	(86,865)	81,232	(86,865)
Total SVBFG Stockholders’ Equity
Stockholders Equity Note [Line Items]
Beginning balance	5,342,773	4,415,446	5,116,209	4,179,795
Common stock issued under employee benefit plans, net of restricted stock cancellations	10,789	7,644	7,853	7,165
Net income	317,987	237,798	606,719	432,759
Net change in unrealized gains and losses on AFS securities, net of tax	86,186	(10,754)	122,597	(52,855)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(519)	(674)	(1,005)	(1,547)
Foreign currency translation adjustments, net of tax	(2,092)	(3,751)	(68)	(1,501)
Net change in unrealized gains and losses on cash flow hedges, net of tax	13,031		13,828
Share-based compensation, net	16,646	11,944	31,768	22,467
Common stock repurchases	(230,758)		(346,781)
Ending balance	5,554,043	4,657,653	5,554,043	4,657,653
Noncontrolling Interests
Stockholders Equity Note [Line Items]
Beginning balance	141,050	144,278	148,634	139,620
Net income	18,584	9,228	21,464	22,293
Capital calls and distributions, net	(7,502)	(6,318)	(23,222)	(14,725)
Ending balance	$ 152,132	$ 147,188	$ 152,132	$ 147,188