Commitments and Contingencies - Location and Amounts of Leases (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Assets
Lease right of use assets	$ 479	$ 494
Liabilities
Current lease liabilities	100	100
Non-current lease liabilities	$ 525	$ 544
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent		us-gaap:OtherLiabilitiesCurrent