Leases - Other Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Other information
Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases	$ 13	$ 14	$ 26	$ 29
Right-of-use assets obtained in exchange for lease liabilities: Operating leases	$ 13	$ 6	$ 21	$ 167
Weighted average remaining lease term (years): Operating leases	5 years 2 months 12 days		5 years 2 months 12 days		5 years 6 months
Weighted average discount rate: Operating leases	5.50%		5.50%		5.70%