Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of the Post-Modification Balance of Loans Restructured) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) contracts	Dec. 31, 2018 USD ($) contracts	Dec. 31, 2017 USD ($) contracts
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	176	71	21
Balance | $	$ 53,565	$ 29,243	$ 24,325
Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	134	67	12
Balance | $	$ 30,716	$ 11,132	$ 4,265
Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	30	28	9
Balance | $	$ 6,020	$ 2,874	$ 4,915
Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	17	3	7
Balance | $	$ 26,676	$ 17,872	$ 17,719
Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	1	1
Balance | $	$ 0	$ 239	$ 69
Commercial | Commercial, industrial and other
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	23	4	5
Balance | $	$ 26,265	$ 13,441	$ 3,775
Commercial | Commercial, industrial and other | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	11	3	1
Balance | $	$ 6,917	$ 691	$ 95
Commercial | Commercial, industrial and other | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	2	0	1
Balance | $	$ 605	$ 0	$ 2,272
Commercial | Commercial, industrial and other | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	13	1	3
Balance | $	$ 20,872	$ 12,750	$ 1,408
Commercial | Commercial, industrial and other | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial | Franchise
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	3	3
Balance | $	$ 0	$ 5,157	$ 16,256
Commercial | Franchise | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	1	0
Balance | $	$ 0	$ 35	$ 0
Commercial | Franchise | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial | Franchise | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	2	3
Balance | $	$ 0	$ 5,122	$ 16,256
Commercial | Franchise | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial | Asset-based lending
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	1	1	0
Balance | $	$ 76	$ 130	$ 0
Commercial | Asset-based lending | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	1	1	0
Balance | $	$ 76	$ 130	$ 0
Commercial | Asset-based lending | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial | Asset-based lending | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial | Asset-based lending | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial | Leases
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	1	0
Balance | $	$ 0	$ 239	$ 0
Commercial | Leases | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	1	0
Balance | $	$ 0	$ 239	$ 0
Commercial | Leases | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial | Leases | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial | Leases | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial real estate | Office
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	2	1	0
Balance | $	$ 5,382	$ 59	$ 0
Commercial real estate | Office | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	2	1	0
Balance | $	$ 5,382	$ 59	$ 0
Commercial real estate | Office | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial real estate | Office | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	1	0	0
Balance | $	$ 5,070	$ 0	$ 0
Commercial real estate | Office | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial real estate | Industrial
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial real estate | Industrial | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial real estate | Industrial | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial real estate | Industrial | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial real estate | Industrial | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Commercial real estate | Mixed use and other
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	5	2	1
Balance | $	$ 1,636	$ 455	$ 1,245
Commercial real estate | Mixed use and other | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	3	2	1
Balance | $	$ 1,083	$ 455	$ 1,245
Commercial real estate | Mixed use and other | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	1	0
Balance | $	$ 0	$ 85	$ 0
Commercial real estate | Mixed use and other | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	2	0	0
Balance | $	$ 423	$ 0	$ 0
Commercial real estate | Mixed use and other | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	0	0
Balance | $	$ 0	$ 0	$ 0
Residential real estate and other
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	145	59	12
Balance | $	$ 20,206	$ 9,762	$ 3,049
Residential real estate and other | Extension at Below Market Terms
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	117	58	10
Balance | $	$ 17,258	$ 9,523	$ 2,925
Residential real estate and other | Reduction of Interest Rate
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	28	27	8
Balance | $	$ 5,415	$ 2,789	$ 2,643
Residential real estate and other | Modification To Interest-only Payments
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	1	0	1
Balance | $	$ 311	$ 0	$ 55
Residential real estate and other | Forgiveness of Debt
Financing Receivables, Modifications [Line Items]
Count (contract) | contracts	0	1	1
Balance | $	$ 0	$ 239	$ 69