Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Allowance for Loan Losses Individually and Collectively Evaluated for Impairment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	$ 37,941	$ 41,793
Financing Receivable, Individually Evaluated for Impairment	170,074	174,861
Collectively Evaluated for Impairment	242,962	213,231
Financing Receivable, Collectively Evaluated for Impairment	28,168,206	22,931,455
Commercial loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	37,675	41,215
Financing Receivable, Individually Evaluated for Impairment	165,835	172,258
Collectively Evaluated for Impairment	223,291	197,368
Financing Receivable, Collectively Evaluated for Impairment	25,138,802	20,304,572
Commercial loans \| Software and internet
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	28,527	23,088
Financing Receivable, Individually Evaluated for Impairment	114,850	110,654
Collectively Evaluated for Impairment	75,040	73,016
Financing Receivable, Collectively Evaluated for Impairment	6,039,905	6,061,877
Commercial loans \| Hardware
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	1,253	8,450
Financing Receivable, Individually Evaluated for Impairment	11,506	36,350
Collectively Evaluated for Impairment	18,472	19,164
Financing Receivable, Collectively Evaluated for Impairment	1,223,051	1,157,249
Commercial loans \| Private equity/venture capital
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	0	330
Financing Receivable, Individually Evaluated for Impairment	3,700	658
Collectively Evaluated for Impairment	98,581	82,138
Financing Receivable, Collectively Evaluated for Impairment	14,106,860	9,951,719
Commercial loans \| Life science/healthcare
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	7,484	9,315
Financing Receivable, Individually Evaluated for Impairment	34,067	21,687
Collectively Evaluated for Impairment	24,696	15,609
Financing Receivable, Collectively Evaluated for Impairment	2,351,545	1,787,140
Commercial loans \| Premium wine
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	0	0
Financing Receivable, Individually Evaluated for Impairment	1,301	2,877
Collectively Evaluated for Impairment	3,355	3,532
Financing Receivable, Collectively Evaluated for Impairment	958,362	870,281
Commercial loans \| Other
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	411	32
Financing Receivable, Individually Evaluated for Impairment	411	32
Collectively Evaluated for Impairment	3,147	3,909
Financing Receivable, Collectively Evaluated for Impairment	459,079	476,306
Consumer loans \| Consumer Loan
Financing Receivable, Impaired [Line Items]
Individually Evaluated for Impairment	266	578
Financing Receivable, Individually Evaluated for Impairment	4,239	2,603
Collectively Evaluated for Impairment	19,671	15,863
Financing Receivable, Collectively Evaluated for Impairment	$ 3,029,404	$ 2,626,883

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=84173941&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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The balance of financing receivables that were collectively evaluated for impairment.

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-Publisher FASB
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