Fair Value Disclosures - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Assets and Liabilities Measured on a Recurring Basis
Derivative assets	$ 191	$ 193
Derivative liabilities	98	121
Level 1 | Fair Value, Measurements, Recurring
Assets and Liabilities Measured on a Recurring Basis
Derivative assets	0	0
Investments and securities	20	22
Total	20	22
Derivative liabilities	0	0
Level 2 | Fair Value, Measurements, Recurring
Assets and Liabilities Measured on a Recurring Basis
Derivative assets	191	193
Investments and securities	0	0
Total	191	193
Derivative liabilities	98	121
Level 3 | Fair Value, Measurements, Recurring
Assets and Liabilities Measured on a Recurring Basis
Derivative assets	0	0
Investments and securities	32	30
Total	32	30
Derivative liabilities	$ 0	$ 0