Commitments and Contingencies General (Details) $ in Millions	Mar. 31, 2018 USD ($)
Supply Commitment [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet risks, liability	$ 453.4
Commitments to Car Operations [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet risks, liability	8.8
Deposits [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet risks, liability	$ 8.7