Balance Sheet Parenthetical (Parentheticals) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Oil and Gas Property, Successful Effort Method, Accumulated Depreciation, Depletion and Amortization	$ 3,045,006,000	$ 2,583,698,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	67,393,867	67,078,853
Common Stock, Shares, Outstanding	67,393,867	67,056,441
Treasury Stock, Shares	0	22,412
Assets Held-for-sale [Member]
Oil and Gas Property, Successful Effort Method, Accumulated Depreciation, Depletion and Amortization	22,482,000	7,390,000
Other Capitalized Property Plant and Equipment [Member]
Oil and Gas Property, Successful Effort Method, Accumulated Depreciation, Depletion and Amortization	$ 35,627,000	$ 28,775,000