Segment and Geographic Area Information - Schedule of Geographic Information for Sales (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 3,174	$ 2,964	$ 2,859	$ 2,655	$ 2,537	$ 2,329	$ 2,323	$ 2,129	$ 11,652	$ 9,318	$ 11,199
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									5,370	4,365	5,386
Spain [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									3,303	2,663	2,852
Western Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									2,266	1,644	2,147
Brazil [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									569	432	562
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									93	141	132
Other Geographical Regions [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales									$ 51	$ 73	$ 120