Parent Company Only Condensed Financial Information Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Cash and cash equivalents	$ 2,923,075	$ 2,545,750	$ 1,503,257	$ 1,811,014	[1]
Investment securities	24,435,172	21,669,961
Net loans	22,851,292	19,674,578
Other assets	876,246	672,688
Total assets	51,214,467	44,683,660
Liabilities and total equity
Other liabilities	911,755	618,383
Total liabilities	46,895,052	40,906,623
SVBFG stockholders' equity	4,179,795	3,642,554
Total liabilities and total equity	51,214,467	44,683,660
Parent Company
Assets:
Cash and cash equivalents	457,324	500,014	$ 377,013	$ 314,236
Investment securities	485,220	244,603
Net loans	0	13,337
Other assets	196,974	197,220
Total assets	4,992,600	4,492,529
Liabilities and total equity
Other liabilities	117,313	100,917
Total liabilities	812,805	849,975
SVBFG stockholders' equity	4,179,795	3,642,554
Total liabilities and total equity	4,992,600	4,492,529
Parent Company | 3.50% Senior Notes
Liabilities and total equity
Notes payable	347,303	346,979
Parent Company | 5.375% Senior Notes
Liabilities and total equity
Notes payable	348,189	347,586
Parent Company | 7.0% Junior Subordinated Debentures
Liabilities and total equity
Notes payable	0	54,493
Parent Company | Bank Subsidiaries
Assets:
Investment in subsidiaries	3,762,542	3,423,427
Parent Company | Nonbank Subsidiaries
Assets:
Investment in subsidiaries	$ 90,540	$ 113,928

[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.