Mortgage Servicing Rights - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Other Noninterest Income
Servicing Assets at Fair Value [Line Items]
Mortgage servicing fees	$ 1.2	$ 1.2

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration