Age Analysis of Past Due Financing receivables (Details) $ in Thousands	Dec. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan		Dec. 31, 2018 USD ($)
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	301	447
Number of Loans 60-89 Days | loan	25	43
Number of Loans 90 Days or More | loan	82	113
Number of Loans Total Past Due | loan	408	603
Principal Balance Total Past Due	$ 21,396	$ 25,485
Current	9,371,470	8,848,154
Total loans	9,392,866	8,873,639		$ 6,906,194
Recorded Investment >90 Days and Accruing	$ 1	$ 2,157
Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	2	1
Number of Loans 60-89 Days | loan	1	2
Number of Loans 90 Days or More | loan	8	5
Number of Loans Total Past Due | loan	11	8
Principal Balance Total Past Due	$ 1,775	$ 1,336
Current	2,101,377	1,393,700
Total loans	2,103,152	1,395,036		1,093,629
Recorded Investment >90 Days and Accruing	$ 0	$ 0
Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	3	7
Number of Loans 60-89 Days | loan	0	1
Number of Loans 90 Days or More | loan	4	8
Number of Loans Total Past Due | loan	7	16
Principal Balance Total Past Due	$ 924	$ 3,922
Current	4,173,003	3,998,437
Total loans	4,173,927	4,002,359		3,251,248
Recorded Investment >90 Days and Accruing	$ 0	$ 218	[1]
Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	0	1
Number of Loans 60-89 Days | loan	2	0
Number of Loans 90 Days or More | loan	0	0
Number of Loans Total Past Due | loan	2	1
Principal Balance Total Past Due	$ 2,794	$ 560
Current	551,135	546,733
Total loans	553,929	547,293		365,165
Recorded Investment >90 Days and Accruing	$ 0	$ 0
Small Business [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	14	11
Number of Loans 60-89 Days | loan	6	3
Number of Loans 90 Days or More | loan	4	6
Number of Loans Total Past Due | loan	24	20
Principal Balance Total Past Due	$ 753	$ 967
Current	174,270	173,530
Total loans	175,023	174,497		164,676
Recorded Investment >90 Days and Accruing	$ 0	$ 0
Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	12	17
Number of Loans 60-89 Days | loan	8	17
Number of Loans 90 Days or More | loan	27	38
Number of Loans Total Past Due | loan	47	72
Principal Balance Total Past Due	$ 11,305	$ 12,312
Current	1,284,878	1,578,257
Total loans	1,296,183	1,590,569		923,294
Recorded Investment >90 Days and Accruing	$ 0	$ 1,652	[1]
Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	10	23
Number of Loans 60-89 Days | loan	5	8
Number of Loans 90 Days or More | loan	33	40
Number of Loans Total Past Due | loan	48	71
Principal Balance Total Past Due	$ 3,569	$ 6,067
Current	1,065,221	1,127,731
Total loans	1,068,790	1,133,798		1,092,084
Recorded Investment >90 Days and Accruing	$ 0	$ 265	[1]
Consumer Portfolio Segment [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days | loan	260	387	[2]
Number of Loans 60-89 Days | loan	3	12	[2]
Number of Loans 90 Days or More | loan	6	16	[2]
Number of Loans Total Past Due | loan	269	415	[2]
Principal Balance Total Past Due	$ 276	$ 321	[2]
Current	21,586	29,766	[2]
Total loans	21,862	30,087	[2]	$ 16,098
Recorded Investment >90 Days and Accruing	1	22	[2]
Financial Asset, 30 to 59 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	4,168	7,511
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	318	253
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	409	1,690
Financial Asset, 30 to 59 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	0	560
Financial Asset, 30 to 59 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	421	837
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	2,150	2,237
Financial Asset, 30 to 59 Days Past Due [Member] | Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	733	1,689
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	137	245	[2]
Financial Asset, 60 to 89 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	9,450	4,155
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	672	323
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	0	194
Financial Asset, 60 to 89 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	2,794	0
Financial Asset, 60 to 89 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	273	15
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	5,507	3,055
Financial Asset, 60 to 89 Days Past Due [Member] | Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	203	524
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	1	44	[2]
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	7,778	13,819
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	785	760
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	515	2,038
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction Loans [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Small Business [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	59	115
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	3,648	7,020
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	2,633	3,854
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Age Analysis of Past Due Financing Receivables
Principal Balance Total Past Due	$ 138	$ 32	[2]

[1] Represents purchased credit impaired ("PCI") loans that were accruing interest due to expectations of future cash collections.

[2] Other consumer portfolio is inclusive of deposit account overdrafts recorded as loan balances.