Loans, Allowance for Credit Losses - Loans, and Credit Quality - Summary of allowance for loan losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ 13,972	$ 13,153	$ 13,153
Provision for credit losses	$ 3,000	$ 300	6,000	500	1,200
Charge-offs			(216)	(232)	(927)
Recoveries			89	150	546
Net (charge-offs) recoveries			(127)	(82)	(381)
Ending balance	$ 29,130	$ 13,571	29,130	$ 13,571	13,972
Adoption of CECL
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			8,488
Ending balance					8,488
Initial PCD ACL
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			797
Ending balance					797
Total impact for adoption of CECL
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance			$ 9,285
Ending balance					$ 9,285