Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Credit Quality Indicators, Broken out by Portfolio Segment and Class of Financing Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	$ 33,327,704	$ 28,511,312
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	32,361,879	27,492,604
Performing (Criticized)
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	812,816	848,634
Performing Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	50,340	75,932
Non Performing Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	102,669	94,142
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	29,553,981	25,480,947
Commercial loans | Software/internet
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	6,255,866	6,209,978
Commercial loans | Hardware
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	1,381,025	1,245,800
Commercial loans | Private equity/venture capital
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	17,817,390	14,118,132
Commercial loans | Life science/healthcare
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	2,427,680	2,461,076
Commercial loans | Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	1,089,576	960,553
Commercial loans | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	582,444	485,408
Commercial loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	28,605,228	24,488,572
Commercial loans | Pass | Software/internet
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	5,704,283	5,574,332
Commercial loans | Pass | Hardware
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	1,266,077	1,146,985
Commercial loans | Pass | Private equity/venture capital
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	17,813,128	14,098,281
Commercial loans | Pass | Life science/healthcare
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	2,197,679	2,291,356
Commercial loans | Pass | Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	1,053,021	909,965
Commercial loans | Pass | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	571,040	467,653
Commercial loans | Performing (Criticized)
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	801,224	826,540
Commercial loans | Performing (Criticized) | Software/internet
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	456,011	520,796
Commercial loans | Performing (Criticized) | Hardware
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	109,490	87,309
Commercial loans | Performing (Criticized) | Private equity/venture capital
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	4,262	16,151
Commercial loans | Performing (Criticized) | Life science/healthcare
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	198,389	135,653
Commercial loans | Performing (Criticized) | Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	24,633	49,287
Commercial loans | Performing (Criticized) | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	8,439	17,344
Commercial loans | Performing Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	50,340	75,612
Commercial loans | Performing Impaired | Software/internet
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	28,417	48,069
Commercial loans | Performing Impaired | Hardware
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	3,315	10,250
Commercial loans | Performing Impaired | Private equity/venture capital
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	0	0
Commercial loans | Performing Impaired | Life science/healthcare
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	5,211	16,276
Commercial loans | Performing Impaired | Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	11,717	1,017
Commercial loans | Performing Impaired | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	1,680	0
Commercial loans | Non Performing Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	97,189	90,223
Commercial loans | Non Performing Impaired | Software/internet
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	67,155	66,781
Commercial loans | Non Performing Impaired | Hardware
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	2,143	1,256
Commercial loans | Non Performing Impaired | Private equity/venture capital
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	0	3,700
Commercial loans | Non Performing Impaired | Life science/healthcare
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	26,401	17,791
Commercial loans | Non Performing Impaired | Premium wine
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	205	284
Commercial loans | Non Performing Impaired | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	1,285	411
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	3,773,723	3,030,365
Consumer loans | Real estate secured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	3,283,445	2,609,645
Consumer loans | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	490,278	420,720
Consumer loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	3,756,651	3,004,032
Consumer loans | Pass | Real estate secured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	3,266,748	2,584,261
Consumer loans | Pass | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	489,903	419,771
Consumer loans | Performing (Criticized)
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	11,592	22,094
Consumer loans | Performing (Criticized) | Real estate secured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	11,217	21,145
Consumer loans | Performing (Criticized) | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	375	949
Consumer loans | Performing Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	0	320
Consumer loans | Performing Impaired | Real estate secured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	0	320
Consumer loans | Performing Impaired | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	0	0
Consumer loans | Non Performing Impaired
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	5,480	3,919
Consumer loans | Non Performing Impaired | Real estate secured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	5,480	3,919
Consumer loans | Non Performing Impaired | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable	$ 0	$ 0