Impairments

The following table summarizes impairment charges recorded during the periods presented:



	Year Ended December 31,
	2012		2011		2010
Oil and gas properties	$	103,417	$	104,688	$	43,067
Other - tubular inventory and well materials	1,067		—		2,892
	$	104,484	$	104,688	$	45,959

The following table summarizes the aggregate fair values of the assets described below, by asset category and the classification of inputs within the fair value measurement hierarchy, at the respective dates of impairment:



	Fair Value
	Measurement		Level 1		Level 2		Level 3
Year ended December 31, 2012:
Long-lived assets held for use	$	14,801	$	—	$	—	$	14,801
Long-lived assets sold during the year	96,099		—		—		96,099

Year ended December 31, 2011:
Long-lived assets held for use	$	26,625	$	—	$	—	$	26,625
Long-lived assets sold during the year	30,342		—		—		30,342

In 2012, we recognized a $28.4 million impairment of our legacy assets in West Virginia, Kentucky and Virginia triggered by the expected disposition of these properties, and a $75.0 million impairment of our Marcellus Shale assets due primarily to market declines in natural gas prices and the resultant reduction in proved natural gas reserves. In 2012, we also recognized an impairment of certain tubular inventory and well materials triggered primarily by declines in asset quality. In 2011, we recognized an impairment of our Arkoma Basin assets for $71.1 million, which was triggered by the expected disposition of these properties. Also during 2011, we recognized impairments of our horizontal coal bed methane properties in the Appalachian region for $26.6 million and certain dry-gas properties in Mississippi for $6.8 million, in each case due primarily to market declines in gas prices. In 2010, we recognized an impairment of our Mid-Continent coal bed methane properties as a result of market declines in gas prices and to an area in the Anadarko Basin of the Mid-Continent region where we drilled an uneconomic well. In addition, we recorded impairment charges attributable to certain tubular inventory and well materials triggered primarily by declines in asset quality.