Commitments and Contingencies (Details)	6 Months Ended
	Jun. 30, 2011 USD ($)	Jun. 30, 2011	Dec. 31, 2010 USD ($)
Commitments and Contingencies (Textuals) [abstract]
Deductible for marine liability coverage including personal injury claims, per first occurrence	$ 10,000,000
Range of deductible for liability coverage for personal injury claims, lower limit	5,000,000
Range of deductible for liability coverage for personal injury claims, upper limit	100,000,000
Estimated liability for personal injury claims	35,400,000		35,000,000
Reserve for personal injury claims recorded in accrued liabilities	8,200,000		11,100,000
Reserve for personal injury claims recorded in other liabilities	27,200,000		23,900,000
Total unconditional purchase obligation	1,800,000,000
First Installments on Drillships	478,300,000
Other Purchase obligations	0		0
Contingent liability under letters of credit and other bonds	72,100,000
Letters of credit issued under revolving credit facility	4,300,000
Principal amount of senior unsecured credit facility	285,000,000
Number of outstanding bonds purchased from related parties		2
Notional amount of outstanding bonds purchased from related parties	19,600,000
Notional amount of performance bonds that may require collateral	56,800,000
Collateral deposits related to agreements	$ 0