Segment and Geographic Area Information - Schedule of Geographic Information for Long-Lived Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 16,426	$ 17,639
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	5,403	4,760
Brazil [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	3,137	3,746
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	2,538	3,024
Iceland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,460	1,518
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,216	1,302
Norway [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	588	762
Russia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	443	471
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	389	388
Spain [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	339	446
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	333	142
Hungary [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	210	211
Jamaica [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets		393
Other Geographical Regions [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 370	$ 476