Acquisitions and Dispositions (Details) (USD $)	1 Months Ended		3 Months Ended		12 Months Ended
	Aug. 31, 2011	Jul. 31, 2010	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2011 Years	Dec. 31, 2010 Years	Dec. 31, 2009	Jul. 20, 2011	May 31, 2011
Acquisitions and Dispositions (Details)
Purchase price for heavy lift derrick barge								$ 62,800,000
Amount of purchase price held in escrow								20,800,000
Purchase of intangible assets				1,500,000
Recognized gain or loss on sale of oil and gas properties				2,800,000			7,300,000
Percentage of proved reserves sold in February and March 2011				12.00%
Percentage of proved reserves sold as of May 31, 2011									79.00%
Base sale price of oil and gas properties									222,300,000
Asset retirement obligations assumed by buyer of oil and gas properties									72,700,000
Net proceeds from sale of oil and gas properties									173,300,000
Buyer's prepayment on sale of oil and gas properties									11,100,000
Recorded amount of net gain on sale of oil and gas properties									56,800,000
Employee retention and incentive benefits paid in connection with sale of oil and gas properties			2,700,000
Percentage of proved reserves sold in August 2011	3.00%
Purchase price for ProServ Offshore, Inc. assets and operations						6,300,000
Purchase price allocation, property, plant, and equipment						6,400,000
Purchase price allocation, intangible assets						600,000
Purchase price allocation, current liabilities						700,000
Acquired intangible assets, useful lives (minimum)					3.0	3.0
Acquired intangible assets, useful lives (maximum)					6.0	6.0
Cost to acquire oil and gas properties		6,700,000			141,000	5,497,000	2,993,000
Aggregate amount of asset retirement obligations assumed by buyers of oil and gas properties					122,000,000		6,300,000
Cash received on sale of oil and gas properties							$ 4,200,000