Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Allowance for Loan Losses Individually and Collectively Evaluated for Impairment (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	$ 44,859
Individually Evaluated for Impairment, Recorded investment in loans	153,009
Collectively Evaluated for Impairment, Allowance for loan losses	260,065
Collectively Evaluated for Impairment, Recorded investment in loans	33,011,627
Commercial loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	44,648
Individually Evaluated for Impairment, Recorded investment in loans	147,529
Collectively Evaluated for Impairment, Allowance for loan losses	238,770
Collectively Evaluated for Impairment, Recorded investment in loans	29,240,421
Commercial loans \| Premium wine
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	204
Individually Evaluated for Impairment, Recorded investment in loans	11,922
Collectively Evaluated for Impairment, Allowance for loan losses	4,944
Collectively Evaluated for Impairment, Recorded investment in loans	1,076,295
Commercial loans \| Other
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	203
Individually Evaluated for Impairment, Recorded investment in loans	2,965
Collectively Evaluated for Impairment, Allowance for loan losses	3,150
Collectively Evaluated for Impairment, Recorded investment in loans	556,689
Commercial loans \| Software/internet
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	26,613
Individually Evaluated for Impairment, Recorded investment in loans	95,572
Collectively Evaluated for Impairment, Allowance for loan losses	73,610
Collectively Evaluated for Impairment, Recorded investment in loans	6,103,976
Commercial loans \| Hardware
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	1,214
Individually Evaluated for Impairment, Recorded investment in loans	5,458
Collectively Evaluated for Impairment, Allowance for loan losses	18,430
Collectively Evaluated for Impairment, Recorded investment in loans	1,365,701
Commercial loans \| Private equity/venture capital
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	0
Individually Evaluated for Impairment, Recorded investment in loans	0
Collectively Evaluated for Impairment, Allowance for loan losses	115,805
Collectively Evaluated for Impairment, Recorded investment in loans	17,801,324
Commercial loans \| Life science/healthcare
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	16,414
Individually Evaluated for Impairment, Recorded investment in loans	31,612
Collectively Evaluated for Impairment, Allowance for loan losses	22,831
Collectively Evaluated for Impairment, Recorded investment in loans	2,336,436
Consumer loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment, Allowance for loan losses	211
Individually Evaluated for Impairment, Recorded investment in loans	5,480
Collectively Evaluated for Impairment, Allowance for loan losses	21,295
Collectively Evaluated for Impairment, Recorded investment in loans	$ 3,771,206

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
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