Loans - Narrative, Troubled Debt Restructurings (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018 USD ($) contract	Jun. 30, 2018 USD ($) contract	Dec. 31, 2017 USD ($)
Receivables [Abstract]
Number of relationships (contract)	0	0
Troubled debt restructurings \| $	$ 17.3	$ 17.3	$ 18.3
Number of TDR loans restructured that subsequently defaulted (contract)		0

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration