Leases - Schedule of Lease Expense and Other Details Related to Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating leases
Operating lease costs	$ 75	$ 75
Variable lease costs	20	20
Supplemental Operating Cash Flows Information
Cash paid for amounts included in the measurement of lease liabilities	77	80
ROU assets obtained in exchange for new lease obligations	$ 80	$ 65
Weighted Average Lease terms and discount rates
Remaining lease term	4 years 5 months 23 days	5 years
Discount rate	3.40%	4.02%