2.2.0.7 true Long-Term Debt (Details) (USD $) 40601 - Disclosure - Long-Term Debt (Details) true false In Millions false false 1 USD false false Unit12 Standard http://www.xbrl.org/2003/instance pure xbrli 0 Unit1 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Unit13 Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 USD true false false false Unsecured Debt [Member] us-gaap_LongtermDebtTypeAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_UnsecuredDebtMember us-gaap_LongtermDebtTypeAxis explicitMember Unit1 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 3 USD true false false false Unsecured Debt [Member] us-gaap_LongtermDebtTypeAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_UnsecuredDebtMember us-gaap_LongtermDebtTypeAxis explicitMember Unit1 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ 5 2010 Credit Facility Initiation Date 3 us-gaap_LineOfCreditFacilityInitiationDate us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 <font class="_mt"><font style="font-family: Times New Roman; font-size: 11pt;" class="_mt">May 28, 2010</font></font> May 28, 2010 true false false 3 false false false false 0 0 true false false us-types:dateStringItemType normalizedstring Reflects when the credit facility first became available, which may be presented in a variety of ways (year, month and year, day, month and year, quarter). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 6 2010 Credit Facility 3 us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity us-gaap true credit instant No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 true true false false 700000000 700.0 true false false 3 false false false false 0 0 true false false xbrli:monetaryItemType monetary Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 7 2010 Credit Facility Expiration Date 3 us-gaap_LineOfCreditFacilityExpirationDate us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 <font class="_mt">four-year term, expiring&nbsp;in May&nbsp;2014</font> four-year term, expiring&nbsp;in May&nbsp;2014 true false false 3 false false false false 0 0 true false false us-types:dateStringItemType normalizedstring Reflects when the credit facility terminates, which may be presented in a variety of ways (year, month and year, day, month and year, quarter). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 8 Credit agreement matured in June 2010 3 us-gaap_LineOfCreditFacilityRevolvingCreditConversionToTermLoanStatus us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 <font class="_mt">350.0</font> 350.0 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false xbrli:stringItemType string Description of whether outstanding balances under the short-term credit facility will be or were transformed into a long-term borrowing arrangement, and indicates when that is expected to occur or when it did occur. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 9 Debt instrument, length in years 3 esv_DebtInstrumentLengthInYears esv false na duration Debt instrument, length in years false false false false false false false false false false false terselabel false 1 false true false false 5 5 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false xbrli:positiveIntegerItemType positiveinteger Debt instrument, length in years No authoritative reference available. false 10 2010 Credit Facility Interest Rate 3 us-gaap_LineOfCreditFacilityInterestRateDescription us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 <font class="_mt">2010 Credit Facility bear interest at LIBOR plus an applicable margin rate (currently 2.0% per annum), depending on our credit rating</font> 2010 Credit Facility bear interest at LIBOR plus an applicable margin rate (currently 2.0% per annum), depending on our credit rating true false false 3 false false false false 0 0 true false false xbrli:stringItemType string Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 11 Annual undrawn facility fee 3 esv_AnnualUndrawnFacilityFee esv false na duration Annual undrawn facility fee false false false false false false false false false false false label false 1 false false false false 0 0 false false false 2 false false false false 0 0 <font class="_mt">annual undrawn facility fee (currently .25% per annum) on the total $700.0 million commitment, which is also based on our credit rating</font> annual undrawn facility fee (currently .25% per annum) on the total $700.0 million commitment, which is also based on our credit rating true false false 3 false false false false 0 0 true false false xbrli:stringItemType string Annual undrawn facility fee No authoritative reference available. false 12 Covenant Terms 3 us-gaap_LineOfCreditFacilityCovenantTerms us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 <font class="_mt">are required to&nbsp;maintain a debt to total capitalization ratio less than or equal to 50% under the 2010 Credit Facility</font> are required to&nbsp;maintain a debt to total capitalization ratio less than or equal to 50% under the 2010 Credit Facility true false false 3 false false false false 0 0 true false false xbrli:stringItemType string Description of the conditions for borrowing under the credit facility including the nature of any restrictions. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 13 2010 Credit Facility Maximum Borrowing Capacity 3 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity us-gaap true credit instant No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false true false false 850000000 850.0 true false false 3 false false false false 0 0 true false false xbrli:monetaryItemType monetary Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 14 2010 Credit Facility Amount Outstanding 3 us-gaap_LineOfCreditFacilityAmountOutstanding us-gaap true credit instant No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 true true false false 0 0 true false false 3 true true false false 0 0 true false false xbrli:monetaryItemType monetary Amount borrowed under the credit facility as of the balance-sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 3 10 false HundredThousands UnKnown UnKnown false true