Allowance for Credit Losses (Summary of the Post-Modification Balance of Loans Restructured) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) contract	Dec. 31, 2019 USD ($) contract	Dec. 31, 2018 USD ($) contract
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	124	176	71
Balance | $	$ 45,872	$ 53,565	$ 29,243
Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	102	134	67
Balance | $	$ 36,467	$ 30,716	$ 11,132
Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	42	30	28
Balance | $	$ 7,721	$ 6,020	$ 2,874
Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	15	17	3
Balance | $	$ 10,479	$ 26,676	$ 17,872
Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	1	0	1
Balance | $	$ 432	$ 0	$ 239
Commercial | Commercial, industrial and other, excluding PPP loans
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	21	24	9
Balance | $	$ 12,362	$ 26,341	$ 18,967
Commercial | Commercial, industrial and other, excluding PPP loans | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	17	12	6
Balance | $	$ 8,089	$ 6,993	$ 1,095
Commercial | Commercial, industrial and other, excluding PPP loans | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	1	2	0
Balance | $	$ 991	$ 605	$ 0
Commercial | Commercial, industrial and other, excluding PPP loans | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	6	13	3
Balance | $	$ 4,436	$ 20,872	$ 17,872
Commercial | Commercial, industrial and other, excluding PPP loans | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	1	0	0
Balance | $	$ 432	$ 0	$ 0
Commercial real estate | Office
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	18	7	3
Balance | $	$ 19,281	$ 7,018	$ 514
Commercial real estate | Office | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	15	5	3
Balance | $	$ 14,657	$ 6,465	$ 514
Commercial real estate | Office | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	3	0	1
Balance | $	$ 921	$ 0	$ 85
Commercial real estate | Office | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	8	3	0
Balance | $	$ 5,853	$ 5,493	$ 0
Commercial real estate | Office | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	0	0	0
Balance | $	$ 0	$ 0	$ 0
Residential real estate and other
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	85	145	59
Balance | $	$ 14,229	$ 20,206	$ 9,762
Residential real estate and other | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	70	117	58
Balance | $	$ 13,721	$ 17,258	$ 9,523
Residential real estate and other | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	38	28	27
Balance | $	$ 5,809	$ 5,415	$ 2,789
Residential real estate and other | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	1	1	0
Balance | $	$ 190	$ 311	$ 0
Residential real estate and other | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contract	0	0	1
Balance | $	$ 0	$ 0	$ 239