Segment Reporting - Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting, Disclosure of Other Information about Entity's Reportable Segments [Abstract]
Number of reportable segments | Segment									3
Segment Reporting Information [Line Items]
Net interest income	$ 514,460	$ 493,222	$ 466,443	$ 419,863	$ 393,706	$ 373,974	$ 342,696	$ 309,993	$ 1,893,988	$ 1,420,369	$ 1,150,523
Provision for credit losses	(13,644)	(17,174)	(29,080)	(27,972)	(22,242)	(23,522)	(15,806)	(30,734)	(87,870)	(92,304)	(106,679)
Noninterest income	186,707	210,070	192,689	155,518	152,266	158,778	128,528	117,659	744,984	557,231	456,552
Noninterest expense	$ (307,592)	$ (309,445)	$ (305,739)	$ (265,417)	$ (264,015)	$ (257,761)	$ (251,246)	$ (237,633)	(1,188,193)	(1,010,655)	(859,797)	[1]
Income before income tax expense									1,362,909	874,641	640,599
Total average loans, net of unearned income									25,630,520	21,159,394	18,283,591
Total average assets									55,229,060	48,380,272	43,987,451
Total average deposits									48,075,344	42,745,148	38,759,059
Global Commercial Bank
Segment Reporting Information [Line Items]
Noninterest income									444,647
Income before income tax expense									1,194,023	848,906
SVB Private Bank
Segment Reporting Information [Line Items]
Noninterest income									2,281
Income before income tax expense									38,780	38,227
SVB Capital
Segment Reporting Information [Line Items]
Noninterest income									101,181
Income before income tax expense									78,412	39,700
Operating segments | Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income									1,623,488	1,274,366	1,040,712
Provision for credit losses									(80,953)	(81,553)	(93,885)
Noninterest income									444,647	363,759	318,366
Noninterest expense									(793,159)	(707,666)	(630,655)
Income before income tax expense											634,538
Total average loans, net of unearned income									22,354,305	18,479,793	16,047,545
Total average assets									53,012,381	46,302,350	41,495,332
Total average deposits									46,039,570	41,043,731	37,301,483
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization									21,800	25,300	24,900
Operating segments | SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income									64,902	58,131	53,582
Provision for credit losses									(3,339)	(4,386)	(1,812)
Noninterest income									2,281	2,175	2,713
Noninterest expense									(25,064)	(17,693)	(12,379)
Income before income tax expense											42,104
Total average loans, net of unearned income									2,850,271	2,423,078	2,025,381
Total average assets									2,546,904	2,449,763	2,047,513
Total average deposits									1,502,308	1,303,542	1,133,425
Operating segments | SVB Capital
Segment Reporting Information [Line Items]
Net interest income									23	48	(49)
Provision for credit losses									0	0	0
Noninterest income									101,181	58,992	49,365
Noninterest expense									(22,792)	(19,340)	(15,546)
Income before income tax expense											33,770
Total average loans, net of unearned income									0	0	0
Total average assets									380,543	325,939	338,848
Total average deposits									0	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income									205,575	87,824	56,278
Provision for credit losses									(3,578)	(6,365)	(10,982)
Noninterest income									196,875	132,305	86,108
Noninterest expense									(347,178)	(265,956)	(201,217)
Income before income tax expense									51,694	(52,192)	(69,813)
Total average loans, net of unearned income									425,944	256,523	210,665
Total average assets									(710,768)	(697,780)	105,758
Total average deposits									$ 533,466	$ 397,875	$ 324,151

[1] Our consolidated statements of income for the year ended December 31, 2016 was modified from prior periods’ presentation to conform to the current period's presentation, which reflects our provision for loan losses and provision for unfunded credit commitments together as our “provision for credit losses”. In prior periods, our provision for unfunded credit commitments were reported separately as a component of noninterest expense.