5. 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 at December 31:



	2017				2016				2015
millions	Impairment		Fair Value ⁽¹⁾		Impairment		Fair Value ⁽¹⁾		Impairment		Fair Value ⁽¹⁾
Exploration and Production
U.S. onshore properties	$	2	$	3	$	28	$	617	$	3,684	$	1,253
Gulf of Mexico properties	227		216		27		61		349		65
Cost-method investment ⁽²⁾	—		—		59		—		3		59
WES Midstream	176		58		16		3		515		36
Other Midstream	2		—		57		29		524		176
Other	1		—		40		—		—		—
Total impairments	$	408	$	277	$	227	$	710	$	5,075	$	1,589

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⁽¹⁾	Measured as of the impairment date using the income approach and Level 3 inputs. The primary assumptions used to estimate undiscounted future net cash flows include anticipated future production, commodity prices, and capital and operating costs.


⁽²⁾	The after-tax net investment fair value was $32 million at December 31, 2015.

2017 Impairments were primarily related to oil and gas properties in the Gulf of Mexico due to lower forecasted commodity prices and a U.S. onshore midstream property due to a reduced throughput fee as a result of a producer’s bankruptcy.

2016 Impairments were primarily related to the uncertain recovery of the Company’s Venezuelan cost-method investment, negative developments related to commercial negotiations of a certain midstream asset, impairment of an office building, changes in development plans for certain U.S. onshore oil and gas assets, and a reduction in estimated future cash flows related to an oil and gas property in the Gulf of Mexico.

2015 Impairments 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.

5. Impairments (Continued)

Impairments of Unproved Properties Impairments of unproved properties are included in exploration expense in the Company’s Consolidated Statements of Income.

2017 The Company recognized $610 million of impairments of unproved Gulf of Mexico properties primarily due to an impairment of $463 million to the Shenandoah project. The unproved property balance related to the Shenandoah project originated from the purchase price allocated to Gulf of Mexico exploration projects from the acquisition of Kerr-McGee Corporation in 2006. The Company also recognized $88 million of impairments of unproved international properties. See Note 6—Suspended Exploratory Well Costs.

2016 The Company recognized a $72 million impairment of unproved properties in the Gulf of Mexico and $92 million of unproved international properties primarily in Brazil and Tunisia due to the Company’s intentions to not pursue future exploration activities.

2015 The Company recognized a $935 million impairment of unproved Greater Natural Buttes properties and a $66 million impairment of an unproved Gulf of Mexico property as a result of lower commodity prices. Also in 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.

It is reasonably possible that significant declines in commodity prices, further changes to the Company’s drilling plans in response to lower prices, reduction of proved and probable reserve estimates, or increases in drilling or operating costs could result in other additional impairments.