Stockholders' Equity and EPS - QTD Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stockholders Equity Note [Line Items]
Balance	$ 4,804,841	$ 4,040,035	$ 4,319,415	$ 3,777,037
Common stock issued under employee benefit plans, net of restricted stock cancellations	1,943	2,370	9,108	14,192
Net income	281,365	154,118	736,417	394,514
Capital calls and distributions, net	(8,060)	(8,613)	(22,785)	(18,216)
Net change in unrealized gains and losses on AFS securities, net of tax	(17,908)	556	(70,763)	(7,491)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(1,283)	(953)	(2,830)	(2,947)
Foreign currency translation adjustments, net of tax	(2,354)	1,141	(3,855)	2,642
Share-based compensation, net	11,501	8,644	33,968	35,473
Balance	5,070,045	4,197,298	5,070,045	4,197,298
Common Stock
Stockholders Equity Note [Line Items]
Balance	$ 53	$ 53	$ 53	$ 52
Balance (in shares)	53,210,627	52,684,159	52,835,188	52,254,074
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)	39,628	39,495	405,395	458,742
Common stock issued under employee benefit plans, net of restricted stock cancellations	$ 0	$ 0	$ 0	$ 1
Balance	$ 53	$ 53	$ 53	$ 53
Balance (in shares)	53,250,255	52,723,654	53,250,255	52,723,654
Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Balance	$ 1,346,586	$ 1,283,485	$ 1,314,377	$ 1,242,741
Common stock issued under employee benefit plans, net of restricted stock cancellations	1,943	2,370	9,108	14,191
Share-based compensation, net	11,501	8,644	33,968	35,473
Balance	1,360,030	1,294,499	1,360,030	1,294,499
Retained Earnings
Stockholders Equity Note [Line Items]
Balance	3,397,879	2,601,007	2,866,837	2,376,331
Net income	274,817	148,620	707,576	373,296
Balance	3,672,696	2,749,627	3,672,696	2,749,627
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Balance	(86,865)	14,890	(1,472)	23,430
Net change in unrealized gains and losses on AFS securities, net of tax	(17,908)	556	(70,763)	(7,491)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(1,283)	(953)	(2,830)	(2,947)
Foreign currency translation adjustments, net of tax	(2,354)	1,141	(3,855)	2,642
Balance	(108,410)	15,634	(108,410)	15,634
Total SVBFG Stockholders’ Equity
Stockholders Equity Note [Line Items]
Balance	4,657,653	3,899,435	4,179,795	3,642,554
Common stock issued under employee benefit plans, net of restricted stock cancellations	1,943	2,370	9,108	14,192
Net income	274,817	148,620	707,576	373,296
Net change in unrealized gains and losses on AFS securities, net of tax	(17,908)	556	(70,763)	(7,491)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(1,283)	(953)	(2,830)	(2,947)
Foreign currency translation adjustments, net of tax	(2,354)	1,141	(3,855)	2,642
Share-based compensation, net	11,501	8,644	33,968	35,473
Balance	4,924,369	4,059,813	4,924,369	4,059,813
Noncontrolling Interests
Stockholders Equity Note [Line Items]
Balance	147,188	140,600	139,620	134,483
Net income	6,548	5,498	28,841	21,218
Capital calls and distributions, net	(8,060)	(8,613)	(22,785)	(18,216)
Balance	$ 145,676	$ 137,485	$ 145,676	$ 137,485