Loans, net and allowance for credit losses- Major Classification of Loans by Past Due Status (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Past Due.
Total Due	$ 2,849,897
Loans		$ 2,730,116
Loans > 90 Days and Accruing	986	748
Financial Assets, Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		3,986
Total Due	5,209
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		2,091
Total Due	2,730
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		367
Total Due	495
Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due.
Total Due		1,528
Total Due	1,984
Financial Assets, Not Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		2,726,130
Total Due	2,844,688
Commercial
Financing Receivable, Recorded Investment, Past Due.
Total Due	368,411
Loans		433,048
Commercial | Financial Assets, Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		261
Total Due	218
Commercial | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		137
Total Due	53
Commercial | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		38
Total Due	155
Commercial | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due.
Total Due		86
Total Due	10
Commercial | Financial Assets, Not Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		432,787
Total Due	368,193
Municipal
Financing Receivable, Recorded Investment, Past Due.
Total Due	175,304
Loans		166,210
Municipal | Financial Assets, Not Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		166,210
Total Due	175,304
Commercial real estate
Financing Receivable, Recorded Investment, Past Due.
Total Due	1,863,118
Loans		1,709,827
Commercial real estate | Financial Assets, Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		438
Total Due	436
Commercial real estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		102
Total Due	152
Commercial real estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		2
Total Due	5
Commercial real estate | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due.
Total Due		334
Total Due	279
Commercial real estate | Financial Assets, Not Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		1,709,389
Total Due	1,862,682
Residential real estate
Financing Receivable, Recorded Investment, Past Due.
Total Due	360,803
Loans		330,728
Loans > 90 Days and Accruing	986	748
Loans in the formal process of foreclosure	300	600
Residential real estate | Financial Assets, Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		2,278
Total Due	3,116
Residential real estate | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		1,162
Total Due	1,456
Residential real estate | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		128
Total Due	50
Residential real estate | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due.
Total Due		988
Total Due	1,610
Residential real estate | Financial Assets, Not Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		328,450
Total Due	357,687
Consumer
Financing Receivable, Recorded Investment, Past Due.
Total Due	82,261
Loans		90,303
Consumer | Financial Assets, Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		1,009
Total Due	1,439
Consumer | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		690
Total Due	1,069
Consumer | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		199
Total Due	285
Consumer | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due.
Total Due		120
Total Due	85
Consumer | Financial Assets, Not Past Due
Financing Receivable, Recorded Investment, Past Due.
Total Due		$ 89,294
Total Due	$ 80,822