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
millions	Impairment		Fair Value⁽¹⁾
March 31, 2016
Oil and gas exploration and production
Long-lived assets held for use
U.S. onshore properties	$	4	$	585
Gulf of Mexico properties	1		—
Cost-method investment ⁽²⁾	1		32
Midstream
Long-lived assets held for use	10		3
Total	$	16	$	620

March 31, 2015
Oil and gas exploration and production
Long-lived assets held for use
U.S. onshore properties	$	2,307	$	1,299
Midstream
Long-lived assets held for use	476		206
Total	$	2,783	$	1,505

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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 first quarter of 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 first quarter of 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.

Potential for Future Impairments During 2015, the Company recognized significant impairments of proved oil and gas and midstream properties and impairments of unproved oil and gas properties, primarily as a result of lower forecasted commodity prices and related changes to the Company’s drilling plans. While commodity prices continued to decline during the first quarter of 2016, the Company did not recognize any material impairments. At March 31, 2016, the Company’s estimate of undiscounted future cash flows attributable to a certain depletion group with a net book value of approximately $2.1 billion indicated that the carrying amount was expected to be recovered; however, this depletion group may be at risk for impairment if the estimates of future cash flows decline. The Company estimates that, if this depletion group becomes impaired in a future period, the Company could recognize non-cash impairments in that period in excess of $1.0 billion. It is also 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 additional impairments.