Segment And Geographic Area Information (Schedule Of Geographic Information For Long-Lived Assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 19,416	$ 20,183
Brazil [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	4,844	5,470
U.S. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	4,573	4,528
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	3,390	3,380
Iceland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,615	1,633
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,447	1,440
Norway [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	894	981
Russia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	531	554
Spain [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	451	483
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	424	410
Jamaica [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	417	435
Other Geographical Regions [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 830	$ 869