Commitments and Contingencies - Guarantees (Details) $ in Millions	Sep. 30, 2017 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Maximum Potential Amount of Future Fundings	$ 394
Recorded Liability for Guarantees	138
Debt service
Commitments and Contingencies Disclosure [Line Items]
Maximum Potential Amount of Future Fundings	136
Recorded Liability for Guarantees	19
Operating profit
Commitments and Contingencies Disclosure [Line Items]
Maximum Potential Amount of Future Fundings	248
Recorded Liability for Guarantees	117
Other
Commitments and Contingencies Disclosure [Line Items]
Maximum Potential Amount of Future Fundings	10
Recorded Liability for Guarantees	$ 2