Commitments and Contingencies - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Cash paid for amounts included in the measurement for operating lease liabilities
Operating cash flows from operating leases	$ 33	$ 36	$ 72	$ 71
Right of use assets obtained in exchange for lease obligations
Operating leases	$ 0	$ 23	$ 6	$ 737