Asset Impairments (Notes)

9 Months Ended

Sep. 30, 2012

Impairments [Abstract]

Asset Impairment Charges [Text Block]

Asset Impairments

Pre-tax (non-cash) asset impairment charges were as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
(millions)
South Raton (Deepwater Gulf of Mexico)	$	—	$	—	$	34	$	—
Piceance (Onshore US)	—		—		39		—
East Texas (Onshore US)	—		—		—		116
Other (Onshore US)	—		—		—		21
Total	$	—	$	—	$	73	$	137

2012 During the second quarter of 2012, we determined that the carrying amounts of our South Raton and Piceance developments were not recoverable from future cash flows and were impaired. The South Raton and Piceance impairments were primarily due to declines in near-term crude oil and natural gas prices, respectively. The assets were written down to their estimated fair values, which were determined using discounted cash flow models.

2011 Due to field performance combined with a low natural gas price environment, we determined that the carrying amounts of certain of our onshore US developments, primarily in East Texas, were not recoverable from future cash flows and, therefore, were impaired. The assets were written down to their estimated fair values, which were determined using discounted cash flow models.

See Note 7. Fair Value Measurements and Disclosures.