Segment Reporting - Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Net interest income	$ 466,443	$ 342,696	$ 886,306	$ 652,689
Provision for credit losses	(29,080)	(15,806)	(57,052)	(46,540)
Noninterest income	192,689	128,528	348,207	246,187
Noninterest expense	(305,739)	(251,246)	(571,156)	(488,879)
Income before income tax expense	324,313	204,172	606,305	363,457
Total average loans, net of unearned income	24,858,503	20,508,541	24,335,762	20,290,141
Total average assets	54,420,646	47,549,364	53,399,616	46,431,410
Total average deposits	47,971,951	42,138,646	47,044,170	41,054,613
Global Commercial Bank
Segment Reporting Information [Line Items]
Noninterest income	113,245		212,591
SVB Private Bank
Segment Reporting Information [Line Items]
Noninterest income	564		1,072
SVB Capital
Segment Reporting Information [Line Items]
Noninterest income	28,498		57,409
Operating segments | Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income	409,057	311,051	778,924	586,929
Provision for credit losses	(27,356)	(14,856)	(52,630)	(43,745)
Noninterest income	113,245	83,904	212,591	163,423
Noninterest expense	(197,695)	(176,702)	(382,261)	(349,548)
Income before income tax expense	297,251	203,397	556,624	357,059
Total average loans, net of unearned income	21,714,870	17,907,635	21,199,897	17,778,065
Total average assets	52,540,865	45,478,211	51,252,398	44,188,162
Total average deposits	45,991,701	40,477,823	45,022,054	39,393,219
Operating segments | SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income	15,645	14,742	31,892	28,352
Provision for credit losses	(300)	(329)	(2,022)	(1,119)
Noninterest income	564	536	1,072	1,254
Noninterest expense	(5,927)	(4,050)	(11,969)	(7,968)
Income before income tax expense	9,982	10,899	18,973	20,519
Total average loans, net of unearned income	2,777,617	2,365,464	2,722,444	2,305,723
Total average assets	2,515,984	2,397,188	2,553,024	2,335,350
Total average deposits	1,480,162	1,302,890	1,526,038	1,319,776
Operating segments | SVB Capital
Segment Reporting Information [Line Items]
Net interest income	9	16	16	16
Provision for credit losses	0	0	0	0
Noninterest income	28,498	15,019	57,409	31,794
Noninterest expense	(5,666)	(6,192)	(10,713)	(9,664)
Income before income tax expense	22,841	8,843	46,712	22,146
Total average loans, net of unearned income	0	0	0	0
Total average assets	369,841	355,292	371,572	364,036
Total average deposits	0	0	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income	41,732	16,887	75,474	37,392
Provision for credit losses	(1,424)	(621)	(2,400)	(1,676)
Noninterest income	50,382	29,069	77,135	49,716
Noninterest expense	(96,451)	(64,302)	(166,213)	(121,699)
Income before income tax expense	(5,761)	(18,967)	(16,004)	(36,267)
Total average loans, net of unearned income	366,016	235,442	413,421	206,353
Total average assets	(1,006,044)	(681,327)	(777,378)	(456,138)
Total average deposits	$ 500,088	$ 357,933	$ 496,078	$ 341,618