Basis of Presentation - Adoption of New Accounting Standards (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable		$ 57,740		$ 57,740		$ 21,606	$ 55,946
Deferred fees		479		479		736	27,057
Current taxes payable		1,616		1,616		2,458	4,675
Retained earnings		3,397,879		3,397,879		2,861,035	2,866,837
Fund management fees		5,929	$ 5,536	11,665	$ 10,705
Income tax expense		77,287	71,656	151,253	123,061
Net income available to common stockholders		$ 237,798	$ 123,193	$ 432,759	$ 224,676
Diluted (dollars per share)		$ 4.42	$ 2.32	$ 8.05	$ 4.22
Reclassification of stranded tax effect for ASU 2018-02	[1]	$ 0	$ 0	$ 319	$ 0
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable							(34,340)
Deferred fees							(26,321)
Current taxes payable							(2,217)
Retained earnings							(5,802)
Cumulative adjustment for ASU, net of tax	[2]						(5,802)
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of stranded tax effect for ASU 2018-02				300
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative adjustment for ASU, net of tax	[2]						74,595
Total SVBFG Stockholders’ Equity | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative adjustment for ASU, net of tax	[2]						(5,802)
Total SVBFG Stockholders’ Equity | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative adjustment for ASU, net of tax						74,600	74,595	[2]
Accumulated Other Comprehensive Income (Loss) | Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of stranded tax effect for ASU 2018-02	[2]			(319)
Accumulated Other Comprehensive Income (Loss) | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative adjustment for ASU, net of tax						$ (29,200)	$ (29,171)	[2]
Balances Without Adoption of ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable		97,584		97,584
Deferred fees		29,964		29,964
Current taxes payable		(924)		(924)
Retained earnings		3,403,357		3,403,357
Fund management fees		6,308		12,914
Income tax expense		77,380		151,577
Net income available to common stockholders		$ 238,084		$ 433,684
Diluted (dollars per share)		$ 4.43		$ 8.07
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable		$ (39,844)		$ (39,844)
Deferred fees		(29,485)		(29,485)
Current taxes payable		2,540		2,540
Retained earnings		(5,478)		(5,478)
Fund management fees		(379)		(1,249)
Income tax expense		(93)		(324)
Net income available to common stockholders		$ (286)		$ (925)
Diluted (dollars per share)		$ (0.01)		$ (0.02)

[1] See "Adoption of New Accounting Standards" in Note 1—“Basis of Presentation” of the “Notes to Interim Consolidated Financial Statements (unaudited)” under Part I, Item 1 of this report for additional details.

[2] See "Adoption of New Accounting Standards" in Note 1—“Basis of Presentation” of the “Notes to Interim Consolidated Financial Statements (unaudited)” under Part I, Item 1 of this report for additional details.