Parent Company Only Condensed Financial Information Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Adjustments to reconcile net income to net cash used for operating activities:
Gains on derivative instruments, net		$ (83,805)	$ (96,845)		$ (42,184)
Gains on investment securities, net		(89,445)	(267,023)		(419,408)
Amortization of share-based compensation		32,239	29,545		25,413
Impairment loss on SVBIF Sale Transaction		0	13,934		0
Other, net		64,660	20,037		(23,851)
Net cash used for operating activities		339,813	255,517		171,778
Cash flows from investing activities:
Net (increase) decrease in loans		(2,335,153)	(3,480,531)		(1,943,650)
Net cash used for investing activities		(6,496,352)	(12,233,931)		(2,838,988)
Cash flows from financing activities:
Tax benefit from stock exercises		16,602	9,602		6,826
Proceeds from issuance of common stock, ESPP, and ESOP		22,410	22,146		46,569
Net proceeds from public equity offering	$ 434,900	0	434,866		0
Net cash provided by financing activities		5,848,782	12,250,649		3,197,006
Net increase (decrease) in cash and cash equivalents		(307,757)	272,235		529,796
Cash and cash equivalents at beginning of period		1,796,062	1,538,779	[1]	1,008,983
Cash and cash equivalents at end of period		1,503,257	1,796,062		1,538,779	[1]
Parent Company
Cash flows from operating activities:
Net income attributable to SVBFG		343,904	263,870		214,517
Adjustments to reconcile net income to net cash used for operating activities:
Gains on derivative instruments, net		(55,477)	(66,604)		(47,421)
Gains on investment securities, net		(39,447)	(8,750)		(15,238)
Net income of subsidiaries		7,551	22,489		18,417
Cash dividends from bank subsidiary		0	0		10,000
Amortization of share-based compensation		32,239	29,545		25,413
Decrease (increase) in other assets		(30,638)	46,512		(9,802)
Increase (decrease) in other liabilities		28,985	25,697		1,506
Impairment loss on SVBIF Sale Transaction		0	9,564		0
Other, net		470	513		(3,368)
Net cash used for operating activities		(71,419)	13,988		(67,327)
Cash flows from investing activities:
Net decrease in investment securities from purchases, sales and maturities		31,380	15,469		70,479
Net (increase) decrease in loans		6,825	(11,893)		4,078
Net cash used for investing activities		(251,247)	(384,514)		63,013
Cash flows from financing activities:
Tax benefit from stock exercises		16,602	9,602		6,826
Proceeds from issuance of common stock, ESPP, and ESOP		22,410	22,146		46,569
Net proceeds from public equity offering		0	434,866		0
Proceeds from Issuance of Long-term Debt		346,431	0		0
Net cash provided by financing activities		385,443	466,614		53,395
Net increase (decrease) in cash and cash equivalents		62,777	96,088		49,081
Cash and cash equivalents at beginning of period		314,236	218,148		169,067
Cash and cash equivalents at end of period		377,013	314,236		218,148
Parent Company | Bank Subsidiaries
Adjustments to reconcile net income to net cash used for operating activities:
Net income of subsidiaries		(306,864)	(249,350)		(184,859)
Cash flows from investing activities:
Investment in subsidiaries		(378,286)	(432,804)		(21,469)
Parent Company | Nonbank Subsidiaries
Adjustments to reconcile net income to net cash used for operating activities:
Net income of subsidiaries		(44,591)	(37,009)		(58,075)
Cash flows from investing activities:
Investment in subsidiaries		$ 88,834	$ 44,714		$ 9,925

[1] 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.