Properties and Equipment (Tables)

3 Months Ended

Mar. 31, 2015

Oil and Gas Property [Abstract]

Property, Plant and Equipment

The following table presents the components of properties and equipment, net of accumulated depreciation, depletion and amortization ("DD&A"):

	March 31, 2015			December 31, 2014
	(in thousands)
Properties and equipment, net:
Crude oil and natural gas properties
Proved	$	2,360,880		$	2,267,165
Unproved	188,518			188,206
Total crude oil and natural gas properties	2,549,398			2,455,371
Equipment and other	31,217			29,562
Land and buildings	9,016			9,015
Construction in progress	178,804			137,937
Properties and equipment, at cost	2,768,435			2,631,885
Accumulated DD&A	(887,432		)	(831,699		)
Properties and equipment, net	$	1,881,003		$	1,800,186

Impairment of natural gas and crude oil properties [Table Text Block]

The following table presents impairment charges recorded for crude oil and natural gas properties:

	Three Months Ended March 31,
	2015		2014
	(in thousands)
Continuing operations:
Amortization of individually insignificant unproved properties	$	2,484	$	910
Discontinued operations:
Amortization of individually insignificant unproved properties	—		69
Total impairment of crude oil and natural gas properties	$	2,484	$	979