Divestitures (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015 rig	Mar. 31, 2014 rig	Dec. 31, 2014 rig
Property, Plant and Equipment Impairment or Disposal [Abstract]
Proceeds from non-core oil and natural gas asset sales, net of related expenses	$ 49,000	$ 8,700,000
Number of drilling rigs removed from service			31
Number of rigs sold	1	4
Net book value of drilling rigs sold	300,000	16,300,000
Gain on sale of drilling rigs	$ 7,900	$ 9,600,000