Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jan. 01, 2019
Sale Leaseback Transaction [Line Items]
Operating lease cost	$ 34	$ 37
Right-of-use assets obtained in exchange for operating lease obligations	$ 14	$ 6
Weighted-average remaining lease term	6 years	6 years
Weighted-average discount rate (percent)	5.80%	6.20%
Adoption of accounting standards			$ 73
Accounting Standards Update 2016-02
Sale Leaseback Transaction [Line Items]
Adoption of accounting standards			$ 73