Summary Of Major Accounting Policies - Acquisitions (Details) (USD $)	Dec. 31, 2011
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 291,617,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount	196,337,000
Business Acquisition, Purchase Price Allocation, Intangible Assets Not Amortizable	60,549,000
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net	34,731,000
Norse Cutting and Abandonment AS [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price	50,296,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount	20,283,000
Business Acquisition, Purchase Price Allocation, Intangible Assets Not Amortizable	13,802,000
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net	16,211,000
AGR Field Operations [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price	220,011,000
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Costs	2,000,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount	165,218,000
Business Acquisition, Purchase Price Allocation, Intangible Assets Not Amortizable	41,387,000
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net	13,406,000
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price	21,310,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount	10,836,000
Business Acquisition, Purchase Price Allocation, Intangible Assets Not Amortizable	5,360,000
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net	$ 5,114,000