Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2013

Property and equipment consisted of the following at December 31, 2013 and 2012 (in thousands):


	2013			2012
Equipment	$	5,749,975		$	5,387,490
Oil and natural gas properties		183,571			156,834
Buildings		80,050			66,490
Land		12,054			10,413

		6,025,650			5,621,227
Less accumulated depreciation and depletion		(2,390,109	)		(2,005,844	)

Property and equipment, net	$	3,635,541		$	3,615,383

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 2013, 2012 and 2011 (in thousands):


	2013		2012		2011
Depreciation and impairment expense	$	573,106	$	502,953	$	419,183
Amortization expense		3,993		4,110		4,110
Depletion expense		20,370		19,551		13,986

Total	$	597,469	$	526,614	$	437,279