Loans - Loan Categories Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Commercial
Schedule of Loans by Loan Classification [Line Items]
Participation loans amount	$ 101.0	$ 104.3
Participations loans sold that are still serviced amount	82.2	80.2
Residential mortgages
Schedule of Loans by Loan Classification [Line Items]
Amount of loans serviced for others	$ 15.0	$ 15.7

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant