Revenue from Contracts with Customers - Contract Liabilities (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2019
Change in Contract with Customer, Liability [Roll Forward]
Balance at December 31, 2018			$ 150
Increase due to cash received, excluding revenues recognized in the period	$ 26		20
Decrease due to revenue recognized		$ (7)	(23)
Balance at June 30, 2019	147		147
Contract liabilities at June 30, 2019
Other current liabilities				$ 19
Other long-term liabilities - other				128
Total contract liabilities from contracts with customers	$ 147		$ 150	$ 147