Allowance for Credit Losses - Reserve for Unfunded Commitments (Details) - Reserve for unfunded commitments - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	$ 30,603	$ 600
Increase (decrease) in Provision	3,500	351
Reserve for unfunded commitments, ending balance	34,103	17,251
Commercial and Industrial
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	11,719
Increase (decrease) in Provision	4,410	(599)
Reserve for unfunded commitments, ending balance	16,129	4,791
Commercial real estate
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	1,328
Increase (decrease) in Provision	(216)	(82)
Reserve for unfunded commitments, ending balance	1,112	696
Construction
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	9,037
Increase (decrease) in Provision	(724)	694
Reserve for unfunded commitments, ending balance	8,313	4,813
Residential mortgage
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	2
Increase (decrease) in Provision	(2)	(6)
Reserve for unfunded commitments, ending balance		1
Home equity
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	8,452
Increase (decrease) in Provision	48	340
Reserve for unfunded commitments, ending balance	8,500	6,927
Consumer
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	65	600
Increase (decrease) in Provision	(16)	4
Reserve for unfunded commitments, ending balance	$ 49	23
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance		16,300
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Commercial and Industrial
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance		5,390
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Commercial real estate
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance		778
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Construction
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance		4,119
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Residential mortgage
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance		7
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Home equity
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance		6,587
ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments | Cumulative-effect adjustment | Consumer
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance		$ (581)