Parent Company Only Condensed Financial Information Condensed Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets:
Cash and cash equivalents	$ 1,796,062	$ 1,538,779	$ 1,008,983	$ 1,114,948
Investment securities	22,690,585	13,582,315
Net loans	14,218,917	10,763,500
Other assets	559,231	465,110
Total assets	39,344,640	26,417,189
Liabilities and total equity
Other liabilities	483,493	404,586
Total liabilities	35,288,216	23,337,861
SVBFG stockholders' equity	2,817,762	1,966,270
Total liabilities and total equity	39,344,640	26,417,189
Parent Company
Assets:
Cash and cash equivalents	314,236	218,148	169,067	137,185
Investment securities	229,604	234,398
Net loans	16,684	4,791
Other assets	159,244	136,897
Total assets	3,273,427	2,393,529
Liabilities and total equity
Other liabilities	52,385	24,030
Total liabilities	455,665	427,259
SVBFG stockholders' equity	2,817,762	1,966,270
Total liabilities and total equity	3,273,427	2,393,529
Parent Company | 5.375% Senior Notes
Liabilities and total equity
Notes payable	348,435	348,209
Parent Company | 7.0% Junior Subordinated Debentures
Liabilities and total equity
Notes payable	54,845	55,020
Parent Company | Bank Subsidiaries
Assets:
Investment in subsidiaries	2,404,101	1,639,024
Parent Company | Nonbank Subsidiaries
Assets:
Investment in subsidiaries	$ 149,558	$ 160,271