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Description Of The Business And Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)
Share data in Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
continent
country
segments
service
rigs
Dec. 31, 2013
Dec. 31, 2012
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Number of rigs under construction 7esv_NumberOfRigsUnderConstruction    
Number of different countries having drilling contracts spanning 20esv_NumberOfDifferentCountriesHavingDrillingContractsSpanning    
Number of different continents having drilling contracts 6esv_NumberOfDifferentContinentsHavingDrillingContracts    
Net foreign currency exchange gains (losses) $ (2,600,000)us-gaap_ForeignCurrencyTransactionGainLossBeforeTax $ 6,400,000us-gaap_ForeignCurrencyTransactionGainLossBeforeTax $ (3,500,000)us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Short-term Investments 757,300,000us-gaap_ShortTermInvestments 50,000,000us-gaap_ShortTermInvestments  
Number of operating segments 3us-gaap_NumberOfOperatingSegments    
Number of reportable segments 2us-gaap_NumberOfReportableSegments    
Number of services 1esv_NumberOfServices    
Antidilutive share options excluded from computation of diluted earnings per share 0.4us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount 0.3us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount 0.4us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Impairment of Long Lived Assets 2,500,000,000esv_ImpairmentofLongLivedAssets    
Deferred Mobilization Costs [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Other assets 95,700,000us-gaap_OtherAssets
/ esv_OperatingExpensesAxis
= esv_DeferredMobilizationCostsMember		 66,600,000us-gaap_OtherAssets
/ esv_OperatingExpensesAxis
= esv_DeferredMobilizationCostsMember		  
Deferred Regulatory Certification And Compliance Costs [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Other assets 20,000,000us-gaap_OtherAssets
/ esv_OperatingExpensesAxis
= esv_DeferredRegulatoryCertificationAndComplianceCostsMember		 18,300,000us-gaap_OtherAssets
/ esv_OperatingExpensesAxis
= esv_DeferredRegulatoryCertificationAndComplianceCostsMember		  
Offshore Drilling Rigs [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Number of contract drilling rigs 70    
Ultra Deepwater Drillships [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Number of contract drilling rigs 10    
Semisubmersible Rigs [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Number of contract drilling rigs 13    
Moored Semisubmersible Rigs [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Number of contract drilling rigs 5    
Jackup Rigs [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Number of contract drilling rigs 42    
Drilling Rigs And Equipment [Member] | Minimum [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Estimated useful lives assets, minimum years 4 years    
Drilling Rigs And Equipment [Member] | Maximum [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Estimated useful lives assets, minimum years 35 years    
Buildings And Improvements [Member] | Minimum [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Estimated useful lives assets, minimum years 2 years    
Buildings And Improvements [Member] | Maximum [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Estimated useful lives assets, minimum years 30 years    
Other Equipment, Computer And Communications Hardware And Software [Member] | Minimum [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Estimated useful lives assets, minimum years 2 years    
Other Equipment, Computer And Communications Hardware And Software [Member] | Maximum [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Estimated useful lives assets, minimum years 6 years    
Capital Reimbursements [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Deferred revenue 428,900,000us-gaap_DeferredRevenue
/ us-gaap_DeferredRevenueArrangementTypeAxis
= esv_CapitalReimbursementsMember		 273,600,000us-gaap_DeferredRevenue
/ us-gaap_DeferredRevenueArrangementTypeAxis
= esv_CapitalReimbursementsMember		  
Mobilization Revenue [Member]      
Description Of The Business And Summary Of Significant Accounting Policies [Line Items]      
Deferred revenue $ 149,400,000us-gaap_DeferredRevenue
/ us-gaap_DeferredRevenueArrangementTypeAxis
= esv_MobilizationRevenueMember		 $ 76,800,000us-gaap_DeferredRevenue
/ us-gaap_DeferredRevenueArrangementTypeAxis
= esv_MobilizationRevenueMember