Commitments and Contingencies - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Cash paid for amounts included in the measurement for operating lease liabilities
Operating cash flows for operating leases	$ 32	$ 32	$ 96	$ 105
Right of use assets obtained in exchange for lease obligations
Operating leases	$ 16	$ 0	$ 18	$ 6