Fair Value Disclosure (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Loans	$ 0.0	$ 6.2
Carrying Amount [Member]
Assets
Investment Funds	0.6	0.6
Loans		6.2
Liabilities
Recourse fixed rate debt	3,971.2	3,858.5
Recourse floating rate debt	426.0	417.8
Estimate of Fair Value Measurement [Member]
Assets
Investment Funds	1.2	1.2
Loans	0.0	6.2
Liabilities
Recourse fixed rate debt	4,089.1	3,852.6
Recourse floating rate debt	428.7	412.2
Not Designated as Hedging Instrument [Member] | Other Expense [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 8.0	$ (2.6)	$ (6.1)
Not Designated as Hedging Instrument [Member] | Aae Cargo Ag [Member] | Other Expense [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net			$ 5.1