millions | 2013 | 2012 | 2011 | ||||||||
Oil and gas exploration and production | |||||||||||
Long-lived assets held for use | |||||||||||
U.S. onshore properties | $ | 142 | $ | 259 | $ | 1,063 | |||||
Gulf of Mexico properties | 562 | 104 | 162 | ||||||||
Cost-method investment | 11 | 13 | 91 | ||||||||
Midstream | |||||||||||
Long-lived assets held for use | 79 | 13 | 458 | ||||||||
Impairments | $ | 794 | $ | 389 | $ | 1,774 |