The following table presents a summary of Devon’s asset impairments. Unproved impairments shown below are included in exploration expenses in the consolidated statements of comprehensive earnings.

	Year Ended December 31,
	2020		2019		2018
Proved oil and gas assets	$	2,664	$	—	$	109
Other assets		29		—		47
Total asset impairments	$	2,693	$	—	$	156

Unproved impairments	$	152	$	18	$	95

Reduced demand from the COVID-19 pandemic caused an unprecedented downturn in the price of oil. As a result, Devon reduced 2020 planned capital spend by 45% in March 2020. With materially lower commodity prices and reduced near-term investment, Devon assessed all of its oil and gas common operating fields for impairment as of March 31, 2020. For impairment determination, Devon historically utilized NYMEX forward strip prices for the first five years and applied internally generated price forecasts for subsequent years. In response to the COVID-19 pandemic, the NYMEX forward market became highly illiquid as evidenced by materially reduced trading volumes for periods beyond 2021. Therefore, Devon supplemented the NYMEX forward strip prices with price forecasts published by reputable investment banks and reservoir engineering firms to estimate future revenues as of March 31, 2020. For WTI, the range of pricing utilized in the first ten years of impairment reserve cash flows was approximately $23 to $50, and the weighted average of WTI pricing was approximately $39. For Henry Hub pricing utilized in the first ten years of impairment reserve cash flows, the range was approximately $1.29 - $2.63, with a weighted average Henry Hub price of approximately $1.85. To measure the indicated impairment in the first quarter of 2020, Devon used a market-based weighted-average cost of capital of 9% to discount the future net cash flows. These inputs are categorized as level 3 in the fair value hierarchy.

Devon recognized approximately $2.7 billion of proved asset impairments during the first quarter of 2020. These impairments related to the Anadarko Basin and Rockies fields in which the cost basis included acquisitions completed in 2016 and 2015, respectively, when commodity prices were much higher than in 2020. During 2020, Devon recognized approximately $29 million of non-oil and gas asset impairments.

In 2018, Devon recognized $109 million of proved asset impairments relating to U.S. non-core assets no longer in its development plans and approximately $47 million of non-oil and gas asset impairments.

Due to the downturn in the commodity price environment and reduced near-term investment as discussed above, Devon recognized $152 million of unproved impairments in 2020. Of these unproved impairments, $116 million related primarily to the Rockies field and $36 million related to certain non-core acreage Devon no longer intends to pursue for exploration opportunities. In 2019 and 2018, Devon allowed certain non-core acreage to expire without plans for development resulting in unproved impairments.