Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property Plant And Equipment [Abstract]

Property and equipment consisted of the following at December 31, 2017 and 2016 (in thousands):

	2017			2016
Equipment	$	8,066,404		$	6,809,129
Oil and natural gas properties		211,566			201,568
Buildings		185,475			97,029
Land		26,593			22,270
Total property and equipment		8,490,038			7,129,996
Less accumulated depreciation, depletion and impairment		(4,235,308	)		(3,721,033	)
Property and equipment, net	$	4,254,730		$	3,408,963

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 2017, 2016 and 2015 (in thousands):

	2017		2016		2015
Depreciation and impairment expense	$	753,510	$	657,571	$	845,543
Amortization expense		21,764		3,643		3,643
Depletion expense		8,067		7,220		15,573
Total	$	783,341	$	668,434	$	864,759