Revenue Recognition - Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Nov. 01, 2017	Oct. 31, 2017	Dec. 31, 2016
Revenue from Contract with Customer [Abstract]
Customer receivables	$ 678	$ 712
Contract assets	32	19
Contract liabilities	423	393
Accounts receivable, gross	691	723
Allowance for doubtful accounts receivable	$ 13	$ 11	$ 3	$ 0	$ 33	$ 29