Allowance for Credit Losses - Reserve for Unfunded Commitments (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Reserve for unfunded commitments:
Adoption of ASU 2016-13			$ 770
Commercial and Industrial
Reserve for unfunded commitments:
Adoption of ASU 2016-13			(16,105)
Commercial real estate
Reserve for unfunded commitments:
Adoption of ASU 2016-13			10,559
Construction
Reserve for unfunded commitments:
Adoption of ASU 2016-13			(1,803)
Lease financing
Reserve for unfunded commitments:
Adoption of ASU 2016-13			207
Consumer
Reserve for unfunded commitments:
Adoption of ASU 2016-13			15,575
Reserve for unfunded commitments
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	$ 23,204	$ 600
Adoption of ASU 2016-13			16,300
Increase (decrease) in Provision	1,400	7,704
Reserve for unfunded commitments, ending balance	24,604	24,604
Reserve for unfunded commitments | Commercial and Industrial
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	8,181
Adoption of ASU 2016-13			5,390
Increase (decrease) in Provision	1,212	4,003
Reserve for unfunded commitments, ending balance	9,393	9,393
Reserve for unfunded commitments | Commercial real estate
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	1,168
Adoption of ASU 2016-13			778
Increase (decrease) in Provision	(57)	333
Reserve for unfunded commitments, ending balance	1,111	1,111
Reserve for unfunded commitments | Construction
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	5,908
Adoption of ASU 2016-13			4,119
Increase (decrease) in Provision	(749)	1,040
Reserve for unfunded commitments, ending balance	5,159	5,159
Reserve for unfunded commitments | Residential mortgage
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	3
Adoption of ASU 2016-13			7
Increase (decrease) in Provision	1	(3)
Reserve for unfunded commitments, ending balance	4	4
Reserve for unfunded commitments | Home equity
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	7,890
Adoption of ASU 2016-13			6,587
Increase (decrease) in Provision	996	2,299
Reserve for unfunded commitments, ending balance	8,886	8,886
Reserve for unfunded commitments | Consumer
Reserve for unfunded commitments:
Reserve for unfunded commitments, beginning balance	54	600
Adoption of ASU 2016-13			$ (581)
Increase (decrease) in Provision	(3)	32
Reserve for unfunded commitments, ending balance	$ 51	$ 51