Stockholders' Equity and EPS - QTD Stockholders' Equity (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	$ 7,468,313,000	$ 5,706,175,000	$ 6,621,080,000	$ 5,264,843,000
Common stock issued under employee benefit plans, net of restricted stock cancellations	4,797,000	1,383,000	15,691,000	9,236,000
Net income	474,055,000	281,718,000	855,493,000	909,901,000
Capital calls and distributions, net	(2,243,000)	(8,780,000)	(16,363,000)	(32,002,000)
Net change in unrealized gains and losses on AFS securities, net of tax	10,018,000	50,638,000	392,725,000	173,235,000
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(266,000)	(270,000)	(765,000)	(1,275,000)
Foreign currency translation adjustments, net of tax	7,475,000	(4,482,000)	871,000	(4,550,000)
Net change in unrealized gains and losses on cash flow hedges, net of tax	(11,568,000)	9,035,000	143,118,000	22,863,000
Share-based compensation, net	21,408,000	18,782,000	60,733,000	50,550,000
Common stock repurchases		(5,730,000)	(60,020,000)	(352,511,000)
Balance, end of period, net of tax	7,967,380,000	$ 6,048,469,000	7,967,380,000	$ 6,048,469,000
Dividends on preferred stock	(4,594,000)		(12,557,000)
Other	$ (15,000)		$ (24,000)
Common Stock
Stockholders Equity Note [Line Items]
Balance (in shares)	51,740,714	51,561,719	51,655,607	52,586,498
Balance, beginning of period, net of tax	$ 52,000	$ 52,000	$ 52,000	$ 53,000
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)	47,258	19,674	364,494	487,101
Common stock issued under employee benefit plans, net of restricted stock cancellations			$ 0	$ 0
Common stock repurchases (in shares)		(25,562)	(244,223)	(1,532,210)
Common stock repurchases			$ 0	$ (1,000)
Balance (in shares)	51,787,972	51,555,831	51,787,972	51,555,831
Balance, end of period, net of tax	$ 52,000	$ 52,000	$ 52,000	$ 52,000
Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	1,522,728,000	1,421,565,000	1,470,071,000	1,378,438,000
Common stock issued under employee benefit plans, net of restricted stock cancellations	4,797,000	1,383,000	15,691,000	9,236,000
Share-based compensation, net	21,408,000	18,782,000	60,733,000	50,550,000
Balance, end of period, net of tax	1,548,918,000	1,441,730,000	1,548,918,000	1,441,730,000
Other	(15,000)		(24,000)
Retained Earnings
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	4,841,720,000	4,051,194,000	4,575,601,000	3,791,838,000
Net income	446,307,000	267,281,000	815,458,000	874,000,000
Common stock repurchases		(5,730,000)	(60,020,000)	(352,510,000)
Balance, end of period, net of tax	5,283,433,000	4,312,745,000	5,283,433,000	4,312,745,000
Dividends on preferred stock	(4,594,000)		(12,557,000)
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	614,735,000	81,232,000	84,445,000	(54,120,000)
Net change in unrealized gains and losses on AFS securities, net of tax	10,018,000	50,638,000	392,725,000	173,235,000
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(266,000)	(270,000)	(765,000)	(1,275,000)
Foreign currency translation adjustments, net of tax	7,475,000	(4,482,000)	871,000	(4,550,000)
Net change in unrealized gains and losses on cash flow hedges, net of tax	(11,568,000)	9,035,000	143,118,000	22,863,000
Balance, end of period, net of tax	620,394,000	136,153,000	620,394,000	136,153,000
Total SVBFG Stockholders’ Equity
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	7,319,373,000	5,554,043,000	6,470,307,000	5,116,209,000
Common stock issued under employee benefit plans, net of restricted stock cancellations	4,797,000	1,383,000	15,691,000	9,236,000
Net income	446,307,000	267,281,000	815,458,000	874,000,000
Net change in unrealized gains and losses on AFS securities, net of tax	10,018,000	50,638,000	392,725,000	173,235,000
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(266,000)	(270,000)	(765,000)	(1,275,000)
Foreign currency translation adjustments, net of tax	7,475,000	(4,482,000)	871,000	(4,550,000)
Net change in unrealized gains and losses on cash flow hedges, net of tax	(11,568,000)	9,035,000	143,118,000	22,863,000
Share-based compensation, net	21,408,000	18,782,000	60,733,000	50,550,000
Common stock repurchases		(5,730,000)	(60,020,000)	(352,511,000)
Balance, end of period, net of tax	7,792,935,000	5,890,680,000	7,792,935,000	5,890,680,000
Dividends on preferred stock	(4,594,000)		(12,557,000)
Other	(15,000)		(24,000)
Noncontrolling Interests
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	148,940,000	152,132,000	150,773,000	148,634,000
Net income	27,748,000	14,437,000	40,035,000	35,901,000
Capital calls and distributions, net	(2,243,000)	(8,780,000)	(16,363,000)	(32,002,000)
Balance, end of period, net of tax	174,445,000	157,789,000	174,445,000	157,789,000
Preferred Stock
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	340,138,000	0	340,138,000	0
Balance, end of period, net of tax	$ 340,138,000	$ 0	$ 340,138,000	$ 0