Commitments and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Loss Contingencies [Line Items]
Level of risk retained by our captive insurance company (per claim)	$ 2.5
Loss Contingency, Receivable	1.5		$ 1.3
Loan subject to loss-sharing arrangements, aggregate unpaid principal amount	6,400.0		5,800.0
Loan loss accrual	13.7		$ 12.2
Loss Contingency Accrual [Roll Forward]
Loss Contingency Accrual	7.3	$ 19.2
Loss Contingency Accrual, Provision	0.3	0.2
Loss Contingency Accrual, Provision Adjustment	0.3	0.2
Loss Contingency Accrual, Payments	(2.3)	(3.0)
Loss Contingency Accrual	$ 5.6	$ 16.6