Parent Company Only Condensed Financial Information - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets:
Cash and cash equivalents	$ 6,781,783		$ 3,571,539	$ 2,923,075	$ 2,545,750
Investment securities	29,071,694		24,218,589
Net loans	32,859,712		28,057,377
Lease right-of-use assets	197,365	$ 146,000	0
Other assets	1,745,233		951,261
Total assets	71,004,903		56,927,979
Liabilities and total equity
Lease liabilities	218,847	$ 178,000	0
Other liabilities	2,041,752		1,006,359
Total liabilities	64,383,823		51,663,136
SVBFG stockholders' equity	6,470,307		5,116,209
Total liabilities and total equity	71,004,903		56,927,979
Parent Company
Assets:
Cash and cash equivalents	800,926		553,049	$ 457,324	$ 500,014
Investment securities	474,842		510,836
Net loans	15,245		0
Lease right-of-use assets	71,847		0
Other assets	214,167		204,301
Total assets	7,043,195		5,939,967
Liabilities and total equity
Other liabilities	136,903		127,293
Total liabilities	572,889		823,758
SVBFG stockholders' equity	6,470,306		5,116,209
Total liabilities and total equity	7,043,195		5,939,967
Parent Company | 3.50% Senior Notes
Liabilities and total equity
Senior Notes	347,987		347,639
Parent Company | 5.375% Senior Notes
Liabilities and total equity
Senior Notes	0		348,826
Lease liabilities	87,999		0
Parent Company | Bank Subsidiary
Assets:
Investment in subsidiaries	5,034,095		4,554,813
Parent Company | Nonbank Subsidiaries
Assets:
Investment in subsidiaries	$ 432,073		$ 116,968