Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Net interest income	$ 512,886	$ 419,863
Provision for credit losses	(28,551)	(27,972)
Noninterest income	280,376	155,518
Noninterest expense	(365,664)	(265,417)
Income before income tax expense	399,047	281,992
Total average loans, net of unearned income	28,388,072	23,807,212
Total average assets	57,528,437	52,367,242
Total average deposits	49,714,209	46,106,081
Global Commercial Bank
Segment Reporting Information [Line Items]
Noninterest income	126,317	98,792
SVB Private Bank
Segment Reporting Information [Line Items]
Noninterest income	510	507
SVB Capital
Segment Reporting Information [Line Items]
Noninterest income	24,845	28,910
SVB Leerink Segment
Segment Reporting Information [Line Items]
Noninterest income	68,117
Operating segments | Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income	445,876	369,867
Provision for credit losses	(26,805)	(25,274)
Noninterest income	126,317	98,792
Noninterest expense	(198,683)	(186,891)
Income before income tax expense	346,705	256,494
Total average loans, net of unearned income	24,798,197	20,679,202
Total average assets	55,883,000	49,953,396
Total average deposits	47,596,868	44,041,634
Operating segments | SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income	11,981	16,247
Provision for credit losses	984	(1,722)
Noninterest income	510	507
Noninterest expense	(7,414)	(6,593)
Income before income tax expense	6,061	8,439
Total average loans, net of unearned income	3,085,883	2,666,658
Total average assets	2,507,131	2,590,476
Total average deposits	1,491,234	1,572,424
Operating segments | SVB Capital
Segment Reporting Information [Line Items]
Net interest income	6	7
Provision for credit losses	0	0
Noninterest income	24,845	28,910
Noninterest expense	(5,782)	(5,046)
Income before income tax expense	19,069	23,871
Total average loans, net of unearned income	0	0
Total average assets	378,732	373,322
Total average deposits	0	0
Operating segments | SVB Leerink Segment
Segment Reporting Information [Line Items]
Net interest income	442	0
Provision for credit losses	0	0
Noninterest income	68,117	0
Noninterest expense	(60,540)	0
Income before income tax expense	8,019	0
Total average loans, net of unearned income	0	0
Total average assets	300,332	0
Total average deposits	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income	54,581	33,742
Provision for credit losses	(2,730)	(976)
Noninterest income	60,587	27,309
Noninterest expense	(93,245)	(66,887)
Income before income tax expense	19,193	(6,812)
Total average loans, net of unearned income	503,992	461,352
Total average assets	(1,540,758)	(549,952)
Total average deposits	$ 626,107	$ 492,023