Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Net interest income	$ 529,403	$ 466,443	$ 1,042,289	$ 886,306
Provision for credit losses	(23,946)	(29,080)	(52,497)	(57,052)
Noninterest income	333,750	192,689	614,126	348,207
Noninterest expense	(383,522)	(305,739)	(749,186)	(571,156)
Income before income tax expense	455,685	324,313	854,732	606,305
Total average loans, net of unearned income	29,406,620	24,858,503	28,900,160	24,335,762
Total average assets	60,700,486	54,420,646	59,123,234	53,399,616
Total average deposits	52,962,208	47,971,951	51,347,180	47,044,170
Global Commercial Bank
Segment Reporting Information [Line Items]
Noninterest income	130,652	111,674	256,969	209,560
SVB Private Bank
Segment Reporting Information [Line Items]
Noninterest income	686	565	1,196	1,072
SVB Capital
Segment Reporting Information [Line Items]
Noninterest income	40,059	29,389	64,904	59,363
SVB Leerink
Segment Reporting Information [Line Items]
Noninterest income	67,000		135,117
Operating segments | Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income	461,752	409,057	907,628	778,924
Provision for credit losses	(18,295)	(27,356)	(45,100)	(52,630)
Noninterest income	130,652	111,674	256,969	209,560
Noninterest expense	(206,902)	(196,992)	(404,147)	(382,251)
Income before income tax expense	367,207	296,383	715,350	553,603
Total average loans, net of unearned income	25,724,704	21,714,870	25,264,010	21,199,897
Total average assets	60,502,170	52,561,973	58,214,465	51,274,033
Total average deposits	51,126,806	45,991,701	49,371,589	45,022,054
Operating segments | SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income	12,277	15,600	24,258	31,847
Provision for credit losses	(853)	(300)	131	(2,022)
Noninterest income	686	565	1,196	1,072
Noninterest expense	(9,526)	(7,974)	(18,378)	(16,199)
Income before income tax expense	2,584	7,891	7,207	14,698
Total average loans, net of unearned income	3,217,597	2,777,617	3,152,104	2,722,444
Total average assets	2,432,358	2,515,984	2,469,804	2,553,024
Total average deposits	1,394,905	1,480,162	1,442,803	1,526,038
Operating segments | SVB Capital
Segment Reporting Information [Line Items]
Net interest income	6	9	12	16
Provision for credit losses	0	0	0	0
Noninterest income	40,059	29,389	64,904	59,363
Noninterest expense	(7,883)	(5,666)	(13,665)	(10,712)
Income before income tax expense	32,182	23,732	51,251	48,667
Total average loans, net of unearned income	0	0	0	0
Total average assets	373,167	369,841	375,934	371,572
Total average deposits	0	0	0	0
Operating segments | SVB Leerink
Segment Reporting Information [Line Items]
Net interest income	242	0	684	0
Provision for credit losses	0	0	0	0
Noninterest income	67,000	0	135,117	0
Noninterest expense	(61,935)	0	(122,475)	0
Income before income tax expense	5,307	0	13,326	0
Total average loans, net of unearned income	0	0	0	0
Total average assets	410,279	0	355,609	0
Total average deposits	0	0	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income	55,126	41,777	109,707	75,519
Provision for credit losses	(4,798)	(1,424)	(7,528)	(2,400)
Noninterest income	95,353	51,061	155,940	78,212
Noninterest expense	(97,276)	(95,107)	(190,521)	(161,994)
Income before income tax expense	48,405	(3,693)	67,598	(10,663)
Total average loans, net of unearned income	464,319	366,016	484,046	413,421
Total average assets	(3,017,488)	(1,027,152)	(2,292,578)	(799,013)
Total average deposits	$ 440,497	$ 500,088	$ 532,788	$ 496,078