4. Impairments

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				Six Months Ended
millions	Impairment		Fair Value⁽¹⁾		Impairment		Fair Value⁽¹⁾
June 30, 2016
Oil and gas exploration and production
Long-lived assets held for use
U.S. onshore properties	$	—	$	—	$	4	$	585
Gulf of Mexico properties	1		—		2		—
Cost-method investment ⁽²⁾	1		32		2		32
Midstream
Long-lived assets held for use	11		2		21		5
Other
Long-lived assets held for use	5		1		5		1
Total	$	18	$	35	$	34	$	623

June 30, 2015
Oil and gas exploration and production
Long-lived assets held for use
U.S. onshore properties	$	4	$	12	$	2,303	$	1,303
Gulf of Mexico properties	17		—		25		—
Cost-method investment ⁽²⁾	1		32		1		32
Midstream
Long-lived assets held for use	8		199		484		202
Total	$	30	$	243	$	2,813	$	1,537

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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 six months ended June 30, 2015, were primarily related to the Company’s Greater Natural Buttes oil and gas and midstream properties in the Rockies, which were impaired due to lower forecasted commodity prices.

In addition to the long-lived asset impairments above, the Company recognized a $935 million impairment of unproved Greater Natural Buttes properties during the six months ended June 30, 2015, as a result of lower commodity prices. Impairments of unproved properties are included in exploration expense in the Company’s Consolidated Statements of Income.

It is reasonably possible that prolonged low or further declines in commodity prices, changes to the Company’s drilling plans in response to lower prices, or increases in drilling or operating costs could result in future impairments.