Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property and equipment consisted of the following at December 31, 2018 and 2017 (in thousands):

	2018			2017
Equipment	$	8,370,933		$	8,066,404
Oil and natural gas properties		219,855			211,566
Buildings		186,736			185,475
Land		26,144			26,593
Total property and equipment		8,803,668			8,490,038
Less accumulated depreciation, depletion and impairment		(4,801,119	)		(4,235,308	)
Property and equipment, net	$	4,002,549		$	4,254,730

Summary of Depreciation, Depletion, Amortization and Impairment Expense related to Property and Equipment and Intangible Assets and Liabilities

Depreciation, depletion, amortization and impairment — The following table summarizes depreciation, depletion, amortization and impairment expense related to property and equipment and intangible assets and liabilities for 2018, 2017 and 2016 (in thousands):

	2018		2017		2016
Depreciation and impairment expense	$	887,155	$	753,510	$	657,571
Amortization expense		18,197		21,764		3,643
Depletion expense		10,966		8,067		7,220
Total	$	916,318	$	783,341	$	668,434