Loans and Allowance for Credit Losses on Loans - Aging of Past Due Loans by Class of Loans (Details) - USD ($)	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Aging of Past Due Loans by Class of Loans
Total Past Due	$ 11,504,000		$ 15,315,000
Current	2,684,520,000		2,518,848,000
Total loan balance	2,696,024,000		2,534,163,000
30-59 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	6,252,000		4,770,000
60-89 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	1,873,000		2,234,000
90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	3,379,000		8,311,000
Commercial
Aging of Past Due Loans by Class of Loans
Total loan balance			603,345,000
Real estate
Aging of Past Due Loans by Class of Loans
Total loan balance			1,897,074,000
Consumer
Aging of Past Due Loans by Class of Loans
Total loan balance			33,744,000
Commercial
Aging of Past Due Loans by Class of Loans
Total loan balance	878,393,000	$ 6,790,000
Commercial | Commercial
Aging of Past Due Loans by Class of Loans
Total Past Due	8,056,000		10,084,000
Current	870,337,000		593,261,000
Total loan balance	878,393,000		603,345,000
Commercial | Commercial | 30-59 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	5,195,000		4,770,000
Commercial | Commercial | 60-89 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	1,873,000		2,097,000
Commercial | Commercial | 90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	988,000		3,217,000
CRE - owner occupied
Aging of Past Due Loans by Class of Loans
Total loan balance	553,463,000	6,994,000
CRE - owner occupied | Real estate
Aging of Past Due Loans by Class of Loans
Total Past Due	29,000		5,094,000
Current	553,434,000		543,813,000
Total loan balance	553,463,000		548,907,000
CRE - owner occupied | Real estate | 90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	29,000		5,094,000
CRE - non-owner occupied
Aging of Past Due Loans by Class of Loans
Current	725,776,000		767,821,000
Total loan balance	725,776,000	11,672,000	767,821,000
CRE - non-owner occupied | Real estate
Aging of Past Due Loans by Class of Loans
Total loan balance	725,776,000		767,821,000
Land and construction
Aging of Past Due Loans by Class of Loans
Total loan balance	138,284,000	1,458,000
Land and construction | Real estate
Aging of Past Due Loans by Class of Loans
Current	138,284,000		147,189,000
Total loan balance	138,284,000		147,189,000
Home equity
Aging of Past Due Loans by Class of Loans
Total loan balance	112,679,000	1,321,000
Home equity | Real estate
Aging of Past Due Loans by Class of Loans
Total Past Due	898,000		137,000
Current	111,781,000		151,638,000
Total loan balance	112,679,000		151,775,000
Home equity | Real estate | 60-89 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due			137,000
Home equity | Real estate | 90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	898,000
Multi-family
Aging of Past Due Loans by Class of Loans
Total loan balance	169,637,000	1,253,000
Multi-family | Real estate
Aging of Past Due Loans by Class of Loans
Current	169,637,000		180,623,000
Total loan balance	169,637,000		180,623,000
Residential mortgages
Aging of Past Due Loans by Class of Loans
Total loan balance	95,033,000	678,000
Residential mortgages | Real estate
Aging of Past Due Loans by Class of Loans
Current	95,033,000		100,759,000
Total loan balance	95,033,000		100,759,000
Consumer and other
Aging of Past Due Loans by Class of Loans
Total loan balance	22,759,000	$ 1,689,000
Consumer and other | Consumer
Aging of Past Due Loans by Class of Loans
Total Past Due	2,521,000
Current	20,238,000		33,744,000
Total loan balance	22,759,000		$ 33,744,000
Consumer and other | Consumer | 30-59 Days Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	1,057,000
Consumer and other | Consumer | 90 Days or Greater Past Due
Aging of Past Due Loans by Class of Loans
Total Past Due	$ 1,464,000