Acquisitions & Divestitures - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) branch	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 06, 2013 USD ($)
Business Combinations [Abstract]
Number of branches sold | branch	2
Sale of deposits as part of branch sale				$ 78.4
Sale of cash and cash equivalents as part of branch sale				0.4
Sale of loans as part of branch sale				7.6
Sale of other assets as part of branch sale				$ 1.0
Gain on sale of branches	$ 1.0
Branches closed | branch	2
Lease abandonment expense	$ 0.1	$ 0.4	$ 0.5
Discontinued Operations, Disposed of by Means Other than Sale, Abandonment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Lease abandonment liability	$ 0.7