Accounting Policies And Disclosures (Details) (USD $)	3 Months Ended				9 Months Ended						3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended			9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended			9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2012 Restatement Adjustment [Member]	Sep. 30, 2012 Restatement Adjustment [Member]	Sep. 30, 2012 Scenario, Previously Reported [Member]	Sep. 30, 2012 Scenario, Previously Reported [Member]	Sep. 30, 2012 UNITED STATES	Jun. 30, 2012 UNITED STATES	Mar. 31, 2012 UNITED STATES	Sep. 30, 2012 UNITED STATES	Sep. 30, 2012 UNITED STATES Restatement Adjustment [Member]	Sep. 30, 2012 UNITED STATES Restatement Adjustment [Member]	Sep. 30, 2012 CANADA	Jun. 30, 2012 CANADA	Mar. 31, 2012 CANADA	Sep. 30, 2012 CANADA	Sep. 30, 2012 CANADA Restatement Adjustment [Member]	Sep. 30, 2012 CANADA Restatement Adjustment [Member]
Significant Accounting Policies [Line Items]
Production	$ 104,546,000		$ 156,288,000	[1]	$ 358,281,000		$ 473,053,000	[1]											$ (300,000)	$ (2,600,000)					$ (1,100,000)	$ (4,400,000)
Shareholders Equity	(964,518,000)		(571,831,000)		(964,518,000)		(571,831,000)		(1,132,797,000)	1,261,919,000
Gain (Loss) on Derivative Instruments, Net, Pretax																			(42,800,000)	100,000					(15,300,000)	200,000
Impairment of Oil and Gas Properties	0		551,132,000	[1]	0		2,068,787,000	[1]							479,905,000	1,042,700,000	178,000,000	1,700,682,000	43,400,000	303,100,000	66,282,000	157,000,000	139,900,000	363,160,000	(39,100,000)	164,200,000
Depletion																			(3,300,000)	(4,600,000)					(5,900,000)	(8,500,000)
Income tax (expense) benefit	(5,966,000)		(166,494,000)	[1]	(18,063,000)		330,575,000	[1]											75,300,000	(900,000)					8,800,000	(40,000,000)
Net income (loss)	10,577,000		(790,520,000)		193,397,000		(1,804,107,000)				138,800,000	419,900,000
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ (8,794,000)		$ (46,615,000)		$ (38,114,000)		$ (44,916,000)				$ (34,700,000)	$ (5,200,000)
Earnings (loss) per common share - diluted	$ 0.06	[2]	$ (4.65)	[1],[2]	$ 1.10	[2]	$ (10.61)	[1],[2]			$ (0.82)	$ (2.47)	$ (3.83)	$ (8.14)

[1] Note 1 contains additional information

[2] For the three months ended September 30, 2013, 6.2 million shares associated with our stock options and 0.2 million shares associated with our unvested restricted stock units were antidilutive; therefore, excluded from the diluted share calculation. For the three months ended September 30, 2012, 5.0 million shares associated with our stock options and 0.3 million shares associated with our unvested restricted stock units were antidilutive; therefore, excluded from the diluted share calculation. For the nine months ended September 30, 2013, 5.5 million shares associated with our stock options and 0.2 million shares associated with our unvested restricted stock units were antidilutive; therefore, excluded from the diluted share calculation. For the nine months ended September 30, 2012, 5.0 million shares associated with our stock options and 0.3 million shares associated with our unvested restricted stock units were antidilutive; therefore, excluded from the diluted share calculation.