Parent Company Only Condensed Financial Information - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets:
Cash and cash equivalents	$ 3,571,539	$ 2,923,075	$ 2,545,750	$ 1,503,257
Investment securities	24,218,589	24,435,172
Other assets	951,261	876,246
Total assets	56,927,979	51,214,467
Liabilities and total equity
Other liabilities	1,006,359	911,755
Total liabilities	51,663,136	46,895,052
SVBFG stockholders' equity	5,116,209	4,179,795
Total liabilities and total equity	56,927,979	51,214,467
Parent Company
Assets:
Cash and cash equivalents	553,049	457,324	$ 500,014	$ 377,013
Investment securities	510,836	485,220
Other assets	204,301	196,974
Total assets	5,939,967	4,992,600
Liabilities and total equity
Other liabilities	127,293	117,313
Total liabilities	823,758	812,805
SVBFG stockholders' equity	5,116,209	4,179,795
Total liabilities and total equity	5,939,967	4,992,600
Parent Company | 3.50% Senior Notes
Liabilities and total equity
Senior Notes	347,639	347,303
Parent Company | 5.375% Senior Notes
Liabilities and total equity
Senior Notes	348,826	348,189
Parent Company | Bank Subsidiaries
Assets:
Investment in subsidiaries	4,554,813	3,762,542
Parent Company | Nonbank Subsidiaries
Assets:
Investment in subsidiaries	$ 116,968	$ 90,540