Noninterest Income - Disaggregation of Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 122,459		$ 233,821
Revenues outside the scope of ASC 606	70,230		114,386
Noninterest income	192,689	$ 128,528	348,207	$ 246,187
Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	98,263		190,276
Revenues outside the scope of ASC 606	14,982		22,315
Noninterest income	113,245		212,591
SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	554		1,063
Revenues outside the scope of ASC 606	10		9
Noninterest income	564		1,072
SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,929		11,665
Revenues outside the scope of ASC 606	22,569		45,744
Noninterest income	28,498		57,409
Other Items
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	17,713		30,817
Revenues outside the scope of ASC 606	32,669		46,318
Noninterest income	50,382		77,135
Spot contract commissions
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	31,548		62,750
Spot contract commissions | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	31,350		62,322
Spot contract commissions | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	144		323
Spot contract commissions | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Spot contract commissions | Other Items
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	54		105
Card interchange fees, gross
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	31,838		61,386
Card interchange fees, gross | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	31,734		61,183
Card interchange fees, gross | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Card interchange fees, gross | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Card interchange fees, gross | Other Items
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	104		203
Merchant service fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,425		6,331
Merchant service fees | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,425		6,331
Merchant service fees | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Merchant service fees | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Merchant service fees | Other Items
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Deposit service charges
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	18,794		36,493
Deposit service charges | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	18,386		35,426
Deposit service charges | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	31		59
Deposit service charges | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Deposit service charges | Other Items
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	377		1,008
Client investment fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	29,452		52,327
Client investment fees | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11,895		22,145
Client investment fees | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	379		681
Client investment fees | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Client investment fees | Other Items
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	17,178		29,501
Fund management fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,929		11,665
Fund management fees | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Fund management fees | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Fund management fees | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,929		11,665
Fund management fees | Other Items
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Correspondent bank rebates
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,473		2,869
Correspondent bank rebates | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,473		2,869
Correspondent bank rebates | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Correspondent bank rebates | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Correspondent bank rebates | Other Items
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0		$ 0