Commitments and Contingencies - Narrative (Details) $ in Millions				12 Months Ended
	Aug. 05, 2015 USD ($)	Nov. 19, 2014 USD ($)	Sep. 14, 2010 USD ($)	Dec. 31, 2015 USD ($) loan lawsuit	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Oct. 28, 2015 USD ($)	Sep. 12, 2014 USD ($)	Jul. 31, 2014 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Rent expense under operating leases				$ 12.9	$ 12.5	$ 13.5
Minimum sublease rentals due in the future				$ 2.3
Number of loans repurchased | loan				1
Principal balance of loans sold with recourse provisions				$ 344.2	355.0
Accounts, Notes, Loans and Financing Receivable [Line Items]
Standby letters of credit, term extended by guarantee (up to)				1 year
Outstanding standby letters of credit				$ 3.3	$ 1.2
Number of lawsuits challenging merger | lawsuit				6
Contract termination fee							$ 69.5
Tax Years 2006 Through 2008
Accounts, Notes, Loans and Financing Receivable [Line Items]
Income tax examination, estimate of possible loss			$ 13.3
Tax Years 2009 Through 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Income tax examination, estimate of possible loss		$ 6.1
Tax Years 2011 Through 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Income tax examination, estimate of possible loss	$ 2.1
Residential | Non-performing loans held-for-sale, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, loans sold								$ 4.0	$ 173.7