Parent Company Only Condensed Financial Information Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Adjustments to reconcile net income to net cash used for operating activities:
Gains on derivative instruments, net		$ (54,555)	$ (37,892)	$ (70,963)
Gains on investment securities, net		(64,603)	(51,740)	(89,445)
Amortization of share-based compensation		36,900	35,494	32,239
Other, net		15,882	41,684	64,044
Net cash used for operating activities		580,099	437,977	339,197
Cash flows from investing activities:
Net (increase) decrease in loans		(3,170,099)	(3,157,281)	(2,328,944)
Net cash used for investing activities		(5,903,730)	1,015,344	(6,495,736)
Cash flows from financing activities:
Repayments of Other Long-term Debt		97,781	0	0
Proceeds from issuance of common stock, ESPP, and ESOP		27,003	26,147	22,410
Tax benefit from stock exercises	[1]	0	(3,640)	16,602
Net cash provided by financing activities		5,700,956	(410,828)	5,848,782
Net increase (decrease) in cash and cash equivalents		377,325	1,042,493	(307,757)
Cash and cash equivalents at beginning of period		2,545,750	1,503,257	1,811,014	[2]
Cash and cash equivalents at end of period		2,923,075	2,545,750	1,503,257
Parent Company
Cash flows from operating activities:
Net income attributable to SVBFG		490,506	382,685	343,904
Adjustments to reconcile net income to net cash used for operating activities:
Gains on derivative instruments, net		(54,555)	(37,892)	(70,963)
Gains on investment securities, net		(37,132)	(20,644)	(39,447)
Net income of subsidiaries		(120,735)	(31,107)	(10,221)
Cash dividends from bank subsidiary		90,000	40,000	0
Amortization of share-based compensation		36,900	35,494	32,239
Decrease (increase) in other assets		12,959	35,699	(30,638)
Increase (decrease) in other liabilities		11,774	15,293	28,985
Other, net		131	2,992	15,956
Net cash used for operating activities		90,812	62,049	(53,647)
Cash flows from investing activities:
Net decrease in investment securities from purchases, sales and maturities		(117,743)	54,737	31,380
Net (increase) decrease in loans		13,337	(3,478)	6,825
Net cash used for investing activities		(108,959)	38,445	(269,019)
Cash flows from financing activities:
Repayments of Other Long-term Debt		51,546	0	0
Proceeds from issuance of common stock, ESPP, and ESOP		27,003	26,147	22,410
Tax benefit from stock exercises		0	(3,640)	16,602
Net proceeds from public equity offering		0	0	346,431
Net cash provided by financing activities		(24,543)	22,507	385,443
Net increase (decrease) in cash and cash equivalents		(42,690)	123,001	62,777
Cash and cash equivalents at beginning of period		500,014	377,013	314,236
Cash and cash equivalents at end of period		457,324	500,014	377,013
Parent Company | Bank Subsidiaries
Adjustments to reconcile net income to net cash used for operating activities:
Net income of subsidiaries		(446,769)	(379,629)	(306,864)
Cash flows from investing activities:
Investment in subsidiaries		(38,927)	(14,738)	(378,286)
Parent Company | Nonbank Subsidiaries
Adjustments to reconcile net income to net cash used for operating activities:
Net income of subsidiaries		(13,002)	(11,949)	(26,819)
Cash flows from investing activities:
Investment in subsidiaries		$ 34,374	$ 1,924	$ 71,062

[1] In 2017 we adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting on a prospective basis with no change to prior period amounts. See Note 2- "Summary of Significant Accounting Policies" of the "Notes to Consolidated Financial Statements" under Part II, Item 8 of this report for additional details.

[2] Cash and cash equivalents at December 31, 2014 included $15.0 million recognized in assets held-for-sale in conjunction with the SVBIF sale transaction. On April 13, 2015 we received net proceeds of $39.3 million consisting of the sales price of $48.6 million less $9.3 million of cash and cash equivalents held by SVBIF that were sold.