Interim Financial Information (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues	$ 142,610,000	$ 183,992,000	$ 184,087,000	$ 182,349,000	$ 138,899,000	$ 86,668,000	$ 99,270,000	$ 98,796,000	$ 693,038,000	$ 423,633,000	$ 348,327,000
Costs and Expenses	122,077,000	143,178,000	98,535,000	109,657,000	86,235,000	67,379,000	68,071,000	71,501,000	473,447,000	293,186,000	281,201,000
Income from operations	20,533,000	40,814,000	85,552,000	72,692,000	52,664,000	19,289,000	31,199,000	27,295,000	219,591,000	130,447,000	67,126,000
Net income	(12,058,000)	(1,284,000)	69,579,000	29,037,000	24,153,000	(2,247,000)	35,401,000	1,503,000	85,274,000	58,810,000	26,611,000
Basic earnings per share	$ (0.31)	$ (0.03)	$ 1.77	$ 0.74	$ 0.62	$ (0.06)	$ 0.90	$ 0.04	$ 2.18	$ 1.50	$ 0.66
Diluted earnings (loss) per share	$ (0.31)	$ (0.03)	$ 1.75	$ 0.73	$ 0.61	$ (0.06)	$ 0.90	$ 0.04	$ 2.15	$ 1.50	$ 0.66
Gains Losses On Extinguishment Of Debt											(2,377,000)
Loss on Abandonment Activities of Non Operated Interests		22,600,000							20,800,000
Parent Company [Member]
Revenues									607,432,000	333,901,000	260,574,000
Costs and Expenses									406,052,000	232,029,000	217,630,000
Income from operations									201,380,000	101,872,000	42,944,000
Net income									85,274,000	58,810,000	26,611,000
Gains Losses On Extinguishment Of Debt											$ (2,377,000)