v2.4.0.6

Share-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2011
Share-Based Compensation [Abstract]
Non-vested share awards granted under long-term incentive plan	495,050
Rate non-vested share awards generally vest	20.00%
Non-vested share awards granted to certain officers vest rate	33.00%
Non-vested share weighted-average grant-date fair value	$ 52.54
Share option granted to certain officers as annual equity awards	91,725
Aggregate grant-date fair value of performance awards granted during period	$ 1.3
Share options granted, increments exercisable annually	33.00%
Share options granted, exercisable period in years	3

X

- Definition

Non-vested share awards granted to certain officers vest rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	esv_
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Rate non-vested share awards generally vest.

+ References

No definition available.

+ Details

Name:	esv_RateNonVestedShareAwardsGenerallyVest
Namespace Prefix:	esv_
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Share-based compensation arrangement by performance-based payment award, grant-date, fair value.

+ References

No definition available.

+ Details

Name:	esv_ShareBasedCompensationArrangementByPerformanceBasedPaymentAwardGrantDateFairValue
Namespace Prefix:	esv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Share options granted, exercisable period in years.

+ References

No definition available.

+ Details

Name:	esv_ShareOptionsGrantedExercisablePeriodInYears
Namespace Prefix:	esv_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Share options granted, increments exercisable annually.

+ References

No definition available.

+ Details

Name:	esv_ShareOptionsGrantedIncrementsExercisableAnnually
Namespace Prefix:	esv_
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	us-gaap_ShareBasedCompensationAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The number of shares issuable under a share-based award plan pertaining to grants made during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The weighted average fair value at grant for nonvested share-based awards issued during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	us-types:perShareItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The quantity of shares issuable on stock options awarded under the plan during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(d)

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration