Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses to total loans ratio		1.45%	1.31%
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	$ 32,915	$ 33,614	$ 33,849	$ 32,915
Provision	2,250	12,499	1,180	2,250
Recoveries	431	346	778
Less: Charge-offs	$ 1,747	1,894	2,193
Balance at end of year		44,565	33,614	33,849
Ending allowance balance:
Allocated to loans individually evaluated for impairment		6,185	1,049
Allocated to loans collectively evaluated for impairment		38,380	32,565
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year		18,338	18,014
Provision		8,417	324
Recoveries		0	0
Less: Charge-offs		0	0
Balance at end of year		26,755	18,338	18,014
Ending allowance balance:
Allocated to loans individually evaluated for impairment		3,454	31
Allocated to loans collectively evaluated for impairment		23,301	18,307
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year		9,129	10,493
Provision		683	(29)
Recoveries		265	734
Less: Charge-offs		561	2,069
Balance at end of year		9,516	9,129	10,493
Ending allowance balance:
Allocated to loans individually evaluated for impairment		2,713	974
Allocated to loans collectively evaluated for impairment		6,803	8,155
Commercial construction
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year		4,149	3,307
Provision		3,280	842
Recoveries		0	0
Less: Charge-offs		1,300	0
Balance at end of year		6,129	4,149	3,307
Ending allowance balance:
Allocated to loans individually evaluated for impairment		0	0
Allocated to loans collectively evaluated for impairment		6,129	4,149
Residential mortgages
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year		1,195	1,160
Provision		335	35
Recoveries		0	0
Less: Charge-offs		0	0
Balance at end of year		1,530	1,195	1,160
Ending allowance balance:
Allocated to loans individually evaluated for impairment		0	0
Allocated to loans collectively evaluated for impairment		1,530	1,195
Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year		536	629
Provision		(114)	(102)
Recoveries		45	9
Less: Charge-offs		0	0
Balance at end of year		467	536	629
Ending allowance balance:
Allocated to loans individually evaluated for impairment		0	0
Allocated to loans collectively evaluated for impairment		467	536
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year		267	246
Provision		(102)	110
Recoveries		36	35
Less: Charge-offs		33	124
Balance at end of year		168	267	$ 246
Ending allowance balance:
Allocated to loans individually evaluated for impairment		18	44
Allocated to loans collectively evaluated for impairment		$ 150	$ 223