Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2015

Property Plant And Equipment [Abstract]

Property and equipment consisted of the following at December 31, 2015 and 2014 (in thousands):

	2015			2014
Equipment	$	6,963,148		$	6,679,894
Oil and natural gas properties		200,923			196,234
Buildings		96,470			83,465
Land		22,370			12,038
Total property and equipment		7,282,911			6,971,631
Less accumulated depreciation, depletion and impairment		(3,362,203	)		(2,840,560	)
Property and equipment, net	$	3,920,708		$	4,131,071

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

Depreciation, depletion, amortization and impairment — The following table summarizes depreciation, depletion, amortization and impairment expense related to property and equipment and intangible assets for 2015, 2014 and 2013 (in thousands):

	2015		2014		2013
Depreciation and impairment expense	$	845,543	$	693,390	$	573,106
Amortization expense		3,643		3,643		3,993
Depletion expense		15,573		21,697		20,370
Total	$	864,759	$	718,730	$	597,469