Balance Sheet Parenthetical (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Oil and Gas Property, Successful Effort Method, Accumulated Depreciation, Depletion and Amortization	$ 2,722,287	$ 2,583,698
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	67,078,853	67,078,853
Common Stock, Shares, Outstanding	67,056,441	67,056,441
Treasury Stock, Shares	22,412	22,412
Assets Held-for-sale [Member]
Oil and Gas Property, Successful Effort Method, Accumulated Depreciation, Depletion and Amortization	31,776	7,390
Other Capitalized Property Plant and Equipment [Member]
Oil and Gas Property, Successful Effort Method, Accumulated Depreciation, Depletion and Amortization	$ 31,013	$ 28,775