Segment Information (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 10,846		$ 11,325		$ 11,966
Long-Lived Assets	30,153		29,346
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	7,609		6,813		6,448
Long-Lived Assets	16,518		14,635
CANADA
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	1,608		1,594		1,551
Long-Lived Assets	9,802		9,794
NORWAY
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	0	[1]	977	[1]
EQUATORIAL GUINEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	1,949		1,977
LIBYAN ARAB JAMAHIRIYA
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	244	[2]	1,106	[2]	1,989	[2]
Other International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	1,385		1,812		1,978
Long-Lived Assets	$ 1,884		$ 1,963

[1] Decrease in 2014 is due to the previously discussed sale of our Norway business.

[2] See Note 12 for discussion of Libya operations.