Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Activity Relating to our Allowance for Credit Losses for Loans (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Decrease in allowance for credit loss	$ (56,000)
Allowance for credit loss, beginning balance	447,765	$ 304,924
Charge-offs	(95,005)	(36,896)
Recoveries	4,853	7,755
Provision (Reduction) for Credit Losses	34,026	248,901
Foreign Currency Translation Adjustments	112	(1,185)
Allowance for credit loss, ending balance	391,751	548,963
Accrued interest receivable and other assets \| Loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable	138,400		$ 126,400
Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		25,464
Investor dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	213,357	82,370
Charge-offs	(14,243)	(33,499)
Recoveries	4,531	4,910
Provision (Reduction) for Credit Losses	(36,667)	151,397
Foreign Currency Translation Adjustments	(45)	(1,101)
Allowance for credit loss, ending balance	166,933	275,701
Investor dependent \| Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		71,624
Investor dependent \| Early stage
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	86,674	26,245
Charge-offs	(14,123)	(10,183)
Recoveries	838	1,573
Provision (Reduction) for Credit Losses	(11,121)	70,214
Foreign Currency Translation Adjustments	(21)	(571)
Allowance for credit loss, ending balance	62,247	127,189
Investor dependent \| Early stage \| Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		39,911
Investor dependent \| Growth Stage
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	126,683	56,125
Charge-offs	(120)	(23,316)
Recoveries	3,693	3,337
Provision (Reduction) for Credit Losses	(25,546)	81,183
Foreign Currency Translation Adjustments	(24)	(530)
Allowance for credit loss, ending balance	104,686	148,512
Investor dependent \| Growth Stage \| Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		31,713
SVB Private Bank
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	53,629	21,551
Charge-offs	0	(581)
Recoveries	2	0
Provision (Reduction) for Credit Losses	(8,567)	54,490
Foreign Currency Translation Adjustments	0	(280)
Allowance for credit loss, ending balance	45,064	87,795
SVB Private Bank \| Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		12,615
SBA loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	1,910
Charge-offs	0
Recoveries	0
Provision (Reduction) for Credit Losses	(1,910)
Foreign Currency Translation Adjustments	0
Allowance for credit loss, ending balance	0
Global Fund Banking
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	45,584	107,285
Charge-offs	(79,912)	0
Recoveries	0	0
Provision (Reduction) for Credit Losses	94,329	19,557
Foreign Currency Translation Adjustments	0	(180)
Allowance for credit loss, ending balance	60,001	56,774
Global Fund Banking \| Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		(69,888)
Cash Flow And Balance Sheet Dependent
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	124,249	80,820
Charge-offs	0	(2,624)
Recoveries	0	2,845
Provision (Reduction) for Credit Losses	(12,758)	25,301
Foreign Currency Translation Adjustments	2	(331)
Allowance for credit loss, ending balance	111,493	104,742
Cash Flow And Balance Sheet Dependent \| Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		(1,269)
Premium Wine And Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance	9,036	12,898
Charge-offs	(850)	(192)
Recoveries	320	0
Provision (Reduction) for Credit Losses	(401)	(1,844)
Foreign Currency Translation Adjustments	155	707
Allowance for credit loss, ending balance	$ 8,260	23,951
Premium Wine And Other \| Impact of adopting ASC 326
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss, beginning balance		$ 12,382

Amount of gain (loss) from converting allowance reserve for credit loss to currency of reporting entity from amount denominated or measured in a different currency, which decreases (increases) the allowance for loan and lease losses.

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