No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Share-Based Compensation [Text Block] No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Share options granted, expiration in years No authoritative reference available. No authoritative reference available. No authoritative reference available. Annual undrawn facility fee No authoritative reference available. Reconciliation of income from continuing operations [Text Block] No authoritative reference available. Establishment of liability and insurance receivable hull and debris removal costs No authoritative reference available. Total Financial Assets No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. ENSCO 74 insurance proceeds No authoritative reference available. Proceeds from sale of ENSCO 50 and ENSCO 51 No authoritative reference available. No authoritative reference available. No authoritative reference available. Singapore dollars cash flow hedges outstanding No authoritative reference available. Selling price of ENSCO 60 No authoritative reference available. No authoritative reference available. No authoritative reference available. Ensco 57 Aggregate Pre-Tax Gain No authoritative reference available. Minimum estimate of ENSCO 74 hull and debris removal costs No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. 7.20% Debentures No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Annual liability coverage limit for wreckage and debris removal costs - ENSCO 74 No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Number of plaintiffs No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Non-refundable deposit for ENSCO 60 No authoritative reference available. Classification of remaining aggregate liability leg and hull removal accrued liabilities and other No authoritative reference available. Civil litigation damages tanker damage No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Gains And Losses On Derivatives Designated As Cash Flow Hedges No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Packaged policy ENSCO 69 Deductible No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Aggregate cash flow hedges outstanding No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Proceeds from sale of discontinued operations (ENSCO 50 and ENSCO 51) received in December 2009 No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. ENSCO 69 insured value, package policy No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Minimum estimate of Ensco 29 removal costs No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Other Marketable Securities Non-current Auction Rate Securities Par Value No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Carrying Values And Estimated Fair Values Of Debt Instruments [Text Block] No authoritative reference available. Classification of remaining aggregate receivable leg and hull removal other assets No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Minimum estimate of ENSCO 74 Leg Removal Costs No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Reconciliation of (loss) income from discontinued operations net No authoritative reference available. Liability insurance self insured retention per multiple occurrence No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Maximum estimate of ENSCO 74 hull and debris removal costs No authoritative reference available. Accrued Liabilities And Other Table [Text Block] No authoritative reference available. No authoritative reference available. No authoritative reference available. Property coverage limit ENSCO 74 wreckage and debris removal costs No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Acquired a KFELS Super B Class design jackup rig, amount paid No authoritative reference available. Share options granted, exercisable period in years No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Distance from original drilling location No authoritative reference available. Liability insurance self insured retention per occurrence No authoritative reference available. Number of written depositions that have taken place No authoritative reference available. Weighted-Average Shares Used in EPS Computations [Text Block] No authoritative reference available. Proceeds from sale of discontinued operations (ENSCO 57) received in December 2009 No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Non-vested share awards granted to certain officers vest rate No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Wreckage and debris removal costs No authoritative reference available. No authoritative reference available. No authoritative reference available. Pre-Tax Income From Ensco 69 Discontinued Operations No authoritative reference available. Ensco 50 And 51 Aggregate Pre Tax Gain No authoritative reference available. No authoritative reference available. No authoritative reference available. Property coverage limit for sue and labor costs No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Net income attributable to Ensco shares [Text Block] No authoritative reference available. ENSCO 29 insurance provision No authoritative reference available. Civil litigation damages pipeline rupture No authoritative reference available. Weighted average assumptions [Text Block] No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Liability coverage limit wreckage and debris removal costs No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Initial multiparty asbestos claims No authoritative reference available. No authoritative reference available. No authoritative reference available. Property insurance self insured retention per occurrence No authoritative reference available. No authoritative reference available. No authoritative reference available. ENSCO 74 insured value No authoritative reference available. No authoritative reference available. No authoritative reference available. Number of segments No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Property coverage limit ENSCO 29 wreckage and debris removal costs No authoritative reference available. No authoritative reference available. No authoritative reference available. Australian dollars cash flow hedges outstanding No authoritative reference available. Liability insurance self insured retention for each occurence thereafter No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Rate non-vested share awards generally vest No authoritative reference available. Estimated Net Gains Associated With Derivative Instruments To Be Reclassified To Earnings No authoritative reference available. No authoritative reference available. No authoritative reference available. Establishment of liability and insurance receivable leg removal costs No authoritative reference available. No authoritative reference available. No authoritative reference available. Debt instrument, length in years No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Maximum estimate of ENSCO 29 wreckage removal costs No authoritative reference available. Dividend yield on share options granted during the period No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Share options granted, increments exercisable annually No authoritative reference available. 4.65% Bonds No authoritative reference available. British pounds cash flow hedges outstanding No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Proceeds from sale of ENSCO 57 No authoritative reference available. No authoritative reference available. No authoritative reference available. Represents the caption on the face of the balance sheet to indicate that the entity has entered into (1) purchase or supply arrangements that will require expending a portion of its resources to meet the terms thereof, and (2) is exposed to potential losses or, less frequently, gains, arising from (a) possible claims against a company's resources due to future performance under contract terms, and (b) possible losses or likely gains from uncertainties that will ultimately be resolved when one or more future events that are deemed likely to occur do occur or fail to occur. This caption alerts the reader that one or more notes to the financial statements disclose pertinent information about the entity's commitments and contingencies. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. 6.36% Bonds No authoritative reference available. Maximum estimate of ENSCO 74 leg removal costs No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Aggregate Derivatives Not Designated As Hedging Instruments Outstanding No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Fair Value Measured On Recurring Basis Supplemental Executive Retirement Plan Assets No authoritative reference available. Net book value and inventory of ENSCO 60 No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Minimum estimate of ENSCO 29 wreckage removal costs No authoritative reference available. Income tax liability associated with gain on intercompany transfer No authoritative reference available. Ensco 57 Aggregate Book Value No authoritative reference available. Lawsuit for ENSCO 69 actual damages No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Comprehensive Income Table [Text Block] No authoritative reference available. Acquired a KFELS Super B Class design jackup rig, amount No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. Other currencies cash flow hedges outstanding No authoritative reference available. Summary of the value of share options granted [Text Block] No authoritative reference available. Ensco 50 And 51 Aggregate Book Value No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available. No authoritative reference available.