Property and equipment consisted of the following at March 31, 2019 and December 31, 2018 (in thousands):

	March 31,			December 31,
	2019			2018
Equipment	$	8,392,658		$	8,370,933
Oil and natural gas properties		221,782			219,855
Buildings		186,989			186,736
Land		26,898			26,144
Total property and equipment		8,828,327			8,803,668
Less accumulated depreciation, depletion and impairment		(4,929,809	)		(4,801,119	)
Property and equipment, net	$	3,898,518		$	4,002,549

The Company reviews its long-lived assets, including property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amounts of certain assets may not be recovered over their estimated remaining useful lives (“triggering events”). In connection with this review, assets are grouped at the lowest level at which identifiable cash flows are largely independent of other asset groupings. The Company estimates future cash flows over the life of the respective assets or asset groupings in its assessment of impairment. These estimates of cash flows are based on historical cyclical trends in the industry as well as the Company’s expectations regarding the continuation of these trends in the future. Provisions for asset impairment are charged against income when estimated future cash flows, on an undiscounted basis, are less than the asset’s net book value. Any provision for impairment is measured at fair value.

The Company concluded that no triggering events occurred during the three months ended March 31, 2019 with respect to its asset groups based on the Company’s results of operations for the three months ended March 31, 2019, management’s expectations of operating results in future periods and the prevailing commodity prices at the time.