4. Impairments

Impairments of Long-Lived Assets Impairments of long-lived assets are included in impairment expense in the Company’s Consolidated Statements of Income. The following summarizes impairments of long-lived assets and the related post-impairment fair values by segment:



	Three Months Ended				Nine Months Ended
millions	Impairment		Fair Value⁽¹⁾		Impairment		Fair Value⁽¹⁾
September 30, 2016
Oil and gas exploration and production
Long-lived assets held for use
U.S. onshore properties	$	23	$	32	$	27	$	617
Gulf of Mexico properties	—		—		2		—
Cost-method investment ⁽²⁾	—		—		2		32
Midstream
Long-lived assets held for use	3		—		24		5
Other
Long-lived assets held for use	1		—		6		—
Total	$	27	$	32	$	61	$	654

September 30, 2015
Oil and gas exploration and production
Long-lived assets held for use
U.S. onshore properties	$	641	$	634	$	2,944	$	1,904
Gulf of Mexico properties	101		94		126		94
Cost-method investment ⁽²⁾	1		32		2		32
Midstream
Long-lived assets held for use	15		7		499		209
Total	$	758	$	767	$	3,571	$	2,239

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⁽¹⁾	Measured as of the impairment date using the income approach and Level 3 inputs.


⁽²⁾	Represents the after-tax net investment.

Impairments during the three and nine months ended September 30, 2016, were primarily related to U.S. onshore oil and gas and midstream properties due to changes in development plans. Impairments during the three months ended September 30, 2015, were primarily related to U.S. onshore oil and gas properties and an oil and gas property in the Gulf of Mexico, all of which were impaired due to lower forecasted commodity prices. Impairments during the nine months ended September 30, 2015, were primarily related to the Company’s Greater Natural Buttes oil and gas and midstream properties, certain other U.S. onshore oil and gas and midstream properties, and oil and gas properties in the Gulf of Mexico, all of which were impaired due to lower forecasted commodity prices.

Impairments of Unproved Properties Impairments of unproved properties are included in exploration expense in the Company’s Consolidated Statements of Income. During the third quarter of 2015, the Company recognized a $109 million impairment of unproved Utica properties resulting from an assignment of mineral interests in settlement of a legal matter. The Company also recognized a $935 million impairment of unproved Greater Natural Buttes properties during the nine months ended September 30, 2015, as a result of lower commodity prices.

4. Impairments (Continued)

Potential for Future Impairments At September 30, 2016, the Company’s estimates of undiscounted future cash flows attributable to a certain international asset group with a net book value of approximately $1.4 billion, and certain U.S. onshore asset groups with a combined net book value of approximately $1.1 billion, indicated that the carrying amounts were expected to be recovered; however, these asset groups may be at risk for impairment if the estimates of future cash flows decline. The Company estimates that a 10% decline in oil prices (with all other assumptions unchanged) could result in a non-cash impairment in excess of $600 million for the international asset group, and a 10% decline in natural-gas prices (with all other assumptions unchanged) could result in non-cash impairments in excess of $400 million for the U.S. onshore asset groups. It is also reasonably possible that prolonged low or further declines in commodity prices, further changes to the Company’s drilling plans in response to lower prices, or increases in drilling or operating costs could result in other additional impairments.