Investments - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Investments
Investment securities pledged to secure public deposits	$ 143.6	$ 157.3
Public deposits	$ 95.8	$ 113.6

Total amount of interest-bearing domestic deposit liabilities, which may include brokered, retail, demand, checking, notice of withdrawal, money market and other interest-bearing deposits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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