Segment and Geographic Area Information - Schedule of Geographic Information for Long-Lived Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 14,815	$ 16,426
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	5,758	5,403
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	2,159	2,538
Brazil [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	2,046	3,137
Iceland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,397	1,460
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,238	1,216
Norway [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	463	588
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	352	389
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	312	333
Russia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	303	443
Spain [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	294	339
Hungary [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	190	210
Other Geographical Regions [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 303	$ 370