Impairment

12 Months Ended

Dec. 31, 2019

The Company assesses the need to impair its oil and gas properties during its quarterly full cost pool ceiling limitation calculation. The Company analyzes various property, plant and equipment for impairment when certain triggering events occur by comparing the carrying values of the assets to their estimated fair values. The full cost pool ceiling limitation and estimated fair values of drilling, midstream, and other assets were determined in accordance with the policies discussed in Note 1.

Impairment for the years ended December 31, 2019, 2018 and 2017 consists of the following (in thousands):


	Year Ended December 31,
	2019		2018		2017
Full cost pool ceiling limitation(1)	$	409,574	$	—	$	—
Drilling assets(2)	—		22		4,019

Midstream assets(3)	—		4,148		—

	$	409,574	$	4,170	$	4,019

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(1) Impairment recorded in the year ended December 31, 2019 largely resulted from a decrease in the trailing twelve-month weighted average SEC prices for oil and natural gas prices in 2019, lower NGL prices, increases in expected operating expenses, and other less significant inputs. See Note 22 for additional discussion of our oil and gas producing properties.

(2) Impairment recorded in the years ended December 31, 2018 and 2017 reflects the write-down of remaining drilling and oilfield services assets classified as held for sale to net realizable value.

(3) Impairment recorded in 2018 reflects the write down of $5.7 million in midstream generator assets classified as held for sale to their net realizable value of $1.6 million.