Noninterest Income - Disaggregation of Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 130,437		$ 364,258
Revenues outside the scope of ASC 606	79,633		194,019
Noninterest income	210,070	$ 158,778	558,277	$ 404,965
Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	102,677		292,953
Revenues outside the scope of ASC 606	11,446		33,761
Noninterest income	114,123		326,714
SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	630		1,693
Revenues outside the scope of ASC 606	(25)		(16)
Noninterest income	605		1,677
SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,479		17,144
Revenues outside the scope of ASC 606	18,944		64,688
Noninterest income	24,423		81,832
Other Income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	21,651		52,468
Revenues outside the scope of ASC 606	49,268		95,586
Noninterest income	70,919		148,054
Spot contract commissions
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	30,041	27,700	92,791	73,707
Spot contract commissions | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	29,776		92,098
Spot contract commissions | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	184		507
Spot contract commissions | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Spot contract commissions | Other Income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	81		186
Card interchange fees, gross
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	34,013		95,399
Card interchange fees, gross | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	33,905		95,088
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 Income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	108		311
Merchant service fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,679		10,010
Merchant service fees | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,677		10,008
Merchant service fees | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2		2
Merchant service fees | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Merchant service fees | Other Income
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	19,588		56,081
Deposit service charges | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	19,207		54,633
Deposit service charges | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	24		83
Deposit service charges | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Deposit service charges | Other Income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	357		1,365
Client investment fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	36,265	15,563	88,592	37,571
Client investment fees | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	14,740		36,885
Client investment fees | SVB Private Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	420		1,101
Client investment fees | SVB Capital
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0		0
Client investment fees | Other Income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	21,105		50,606
Fund management fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,479	$ 5,198	17,144	$ 15,903
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	5,479		17,144
Fund management fees | Other Income
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	1,372		4,241
Correspondent bank rebates | Global Commercial Bank
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,372		4,241
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 Income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0		$ 0