Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2012 Unit	Jun. 30, 2012	Dec. 31, 2012 Unit	Dec. 31, 2011	Dec. 31, 2010
Summary Of Significant Accounting Policies [Line Items]
Number of daywork contracts			27
Book overdrafts	$ 7,000,000		$ 7,000,000	$ 26,500,000
Concentration of cash	40,400,000		40,400,000	31,100,000
Minimum depreciation percentage for idle drilling rigs			20.00%
Impairment of Long-Lived Assets Held-for-use	1,200,000		1,200,000
Goodwill impairment			0	0	0
Additions to goodwill			0	0	0
Goodwill deductible for tax purposes	4,800,000		4,800,000	5,700,000	6,500,000
Intangible asset impairment			0	0	0
Amortization on intangible assets			1,200,000	1,200,000	2,600,000
Accumulated amortization on intangible assets	17,300,000		17,300,000	16,100,000
Amortization to be recorded in 2013 on intangible assets	700,000		700,000
Directly related overhead costs capitalized	17,600,000		17,600,000	15,600,000	13,400,000
Average rates used for depreciation, depletion and amortization per Boe			14.70	15.06	11.94
Undeveloped leasehold properties excluded from DD&A calculation	521,659,000		521,659,000
Future discounted net cash flows discounted			10.00%
Impairment of oil and natural gas properties	167,700,000	115,900,000	283,606,000	0	0
Non-cash ceiling test write-down net of tax	104,400,000	72,100,000
Effects of cash flow hedges	29,800,000	32,500,000	29,800,000
Elimination of inter-segment revenue			49,600,000	52,200,000	40,100,000
Eliminated associated operating expense			34,100,000	32,600,000	31,000,000
Eliminated yielding			15,500,000	19,600,000	9,100,000
Number of partnerships	16		16
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days for drilling of one well			20 days
Duration length of contracts			0 years 6 months
Insurance coverage	50,000		50,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days for drilling of one well			90 days
Duration length of contracts			3 years
Insurance coverage	1,500,000		1,500,000
Under-Produced Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Natural gas balancing (MMcf)	5,100		5,100
Over-Produced Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Natural gas balancing (MMcf)	4,550		4,550
Natural Gas Balancing [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable	2,400,000		2,400,000
Liability recognized to under production	$ 3,800,000		$ 3,800,000
Jul'12 - Dec'12 [Member]
Summary Of Significant Accounting Policies [Line Items]
Portion of Future Oil and Gas Production Being Hedged, as of the Reporting Period (MMBoe)		2.9
Jan'13 - Dec'13 [Member]
Summary Of Significant Accounting Policies [Line Items]
Portion of Future Oil and Gas Production Being Hedged, as of the Reporting Period (MMBoe)	6.9	4.5	6.9
Property, Plant and Equipment, Other Types [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful Life, years			3 years
Property, Plant and Equipment, Other Types [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful Life, years			15 years
Drilling Equipment [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful Life, years			15 years