Leases - Supplemental Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$ 32	$ 35
Operating cash flows for financing leases	5	1
Financing cash flows for finance leases	0	10
Operating lease right-of-use assets obtained in exchange for new operating lease liabilities	$ 19	$ 21