Stockholders' Equity and EPS - QTD Stockholders' Equity (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	$ 7,183,221,000	$ 5,483,823,000	$ 6,621,080,000	$ 5,264,843,000
Common stock issued under employee benefit plans, net of restricted stock cancellations	13,925,000	10,789,000	10,894,000	7,853,000
Net income	247,789,000	336,571,000	381,438,000	628,183,000
Capital calls and distributions, net	(13,792,000)	(7,502,000)	(14,120,000)	(23,222,000)
Net change in unrealized gains and losses on AFS securities, net of tax	33,784,000	86,186,000	382,707,000	122,597,000
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(100,000)	(519,000)	(499,000)	(1,005,000)
Foreign currency translation adjustments, net of tax	(40,000)	(2,092,000)	(6,604,000)	(68,000)
Net change in unrealized gains and losses on cash flow hedges, net of tax	(11,443,000)	13,031,000	154,686,000	13,828,000
Share-based compensation, net	20,154,000	16,646,000	39,325,000	31,768,000
Common stock repurchases		(230,758,000)	(60,020,000)	(346,781,000)
Balance, end of period, net of tax	7,468,313,000	$ 5,706,175,000	7,468,313,000	$ 5,706,175,000
Dividends on preferred stock	(4,594,000)		(7,963,000)
Other	$ (591,000)		$ (9,000)
Common Stock
Stockholders Equity Note [Line Items]
Balance (in shares)	51,490,342	52,322,105	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)	250,372	257,684	317,236	467,427
Common stock issued under employee benefit plans, net of restricted stock cancellations			$ 0	$ 0
Common stock repurchases (in shares)		(1,018,070)	(244,223)	(1,506,648)
Common stock repurchases			$ 0	$ (1,000)
Balance (in shares)	51,740,714	51,561,719	51,740,714	51,561,719
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	1,489,240,000	1,394,130,000	1,470,071,000	1,378,438,000
Common stock issued under employee benefit plans, net of restricted stock cancellations	13,925,000	10,789,000	10,894,000	7,853,000
Share-based compensation, net	20,154,000	16,646,000	39,325,000	31,768,000
Balance, end of period, net of tax	1,522,728,000	1,421,565,000	1,522,728,000	1,421,565,000
Other	(591,000)		(9,000)
Retained Earnings
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	4,612,785,000	3,963,965,000	4,575,601,000	3,791,838,000
Net income	233,529,000	317,987,000	369,151,000	606,719,000
Common stock repurchases		(230,758,000)	(60,020,000)	(346,780,000)
Balance, end of period, net of tax	4,841,720,000	4,051,194,000	4,841,720,000	4,051,194,000
Dividends on preferred stock	(4,594,000)		(7,963,000)
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	592,534,000	(15,374,000)	84,445,000	(54,120,000)
Net change in unrealized gains and losses on AFS securities, net of tax	33,784,000	86,186,000	382,707,000	122,597,000
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(100,000)	(519,000)	(499,000)	(1,005,000)
Foreign currency translation adjustments, net of tax	(40,000)	(2,092,000)	(6,604,000)	(68,000)
Net change in unrealized gains and losses on cash flow hedges, net of tax	(11,443,000)	13,031,000	154,686,000	13,828,000
Balance, end of period, net of tax	614,735,000	81,232,000	614,735,000	81,232,000
Total SVBFG Stockholders’ Equity
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	7,034,749,000	5,342,773,000	6,470,307,000	5,116,209,000
Common stock issued under employee benefit plans, net of restricted stock cancellations	13,925,000	10,789,000	10,894,000	7,853,000
Net income	233,529,000	317,987,000	369,151,000	606,719,000
Net change in unrealized gains and losses on AFS securities, net of tax	33,784,000	86,186,000	382,707,000	122,597,000
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(100,000)	(519,000)	(499,000)	(1,005,000)
Foreign currency translation adjustments, net of tax	(40,000)	(2,092,000)	(6,604,000)	(68,000)
Net change in unrealized gains and losses on cash flow hedges, net of tax	(11,443,000)	13,031,000	154,686,000	13,828,000
Share-based compensation, net	20,154,000	16,646,000	39,325,000	31,768,000
Common stock repurchases		(230,758,000)	(60,020,000)	(346,781,000)
Balance, end of period, net of tax	7,319,373,000	5,554,043,000	7,319,373,000	5,554,043,000
Dividends on preferred stock	(4,594,000)		(7,963,000)
Other	(591,000)		(9,000)
Noncontrolling Interests
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	148,472,000	141,050,000	150,773,000	148,634,000
Net income	14,260,000	18,584,000	12,287,000	21,464,000
Capital calls and distributions, net	(13,792,000)	(7,502,000)	(14,120,000)	(23,222,000)
Balance, end of period, net of tax	148,940,000	152,132,000	148,940,000	152,132,000
Preferred Stock
Stockholders Equity Note [Line Items]
Balance, beginning of period, net of tax	340,138	0	340,138	0
Balance, end of period, net of tax	$ 340,138	$ 0	$ 340,138	$ 0