Loans, Allowance for Loan Losses and Allowance for Unfunded Credit Commitments - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) class_financing_receivable portfolio_segment risk_based_segment	Dec. 31, 2019 USD ($)
Receivables [Abstract]
Number of portfolio segments | portfolio_segment	6
Number of financing receivable classes | class_financing_receivable	10
Number of risk-based segments | risk_based_segment	11
Financing Receivable, Allowance for Credit Loss [Line Items]
Unearned income on loans	$ 226,000	$ 163,000
Loans, amortized cost	45,181,488	33,164,636
Real estate secured loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	4,939,569	4,146,347
Credit card receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	400,000	395,000
Construction loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	118,000	183,000
Private Bank
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans reported in Other under historical definitions	427,000
Loans, amortized cost	4,901,056	3,492,269
Private Bank | Real estate secured loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	4,058,679	3,325,617
Private Bank | Loans for personal residence | Real estate secured loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	3,392,237	2,829,880
Private Bank | Loans to eligible employees | Real estate secured loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	481,098	401,396
Private Bank | Home equity lines of credit | Real estate secured loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	42,449	55,461
Private Bank | Other | Real estate secured loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	142,895	38,880
Premium wine
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans reported in Other under historical definitions	53,000
Loans, amortized cost	1,052,643	1,062,264
Premium wine | Real estate secured loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	824,008	820,730
Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	27,687	867,723
Other | Real estate secured loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans, amortized cost	$ 56,882	$ 0