Commitments and Contingencies - Guarantees (Details) $ in Millions	Mar. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Maximum Potential Amount of Future Fundings	$ 373
Recorded Liability for Guarantees	186
Debt service
Commitments and Contingencies Disclosure [Line Items]
Maximum Potential Amount of Future Fundings	131
Recorded Liability for Guarantees	76
Operating profit
Commitments and Contingencies Disclosure [Line Items]
Maximum Potential Amount of Future Fundings	232
Recorded Liability for Guarantees	108
Other
Commitments and Contingencies Disclosure [Line Items]
Maximum Potential Amount of Future Fundings	10
Recorded Liability for Guarantees	$ 2