2.2.0.25falsefalse06121 - Disclosure - Stock-Based Compensation (Details 1)truefalsefalse1falsefalseUSDfalsefalse1/1/2010 - 12/31/2010 USD ($) USD ($) / shares $Jan-01-2010_Dec-31-2010http://www.sec.gov/CIK0000065984duration2010-01-01T00:00:002010-12-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDEPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2009 - 12/31/2009 USD ($) USD ($) / shares $TwelveMonthsEnded_31Dec2009http://www.sec.gov/CIK0000065984duration2009-01-01T00:00:002009-12-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDEPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3falsefalseUSDfalsefalse1/1/2008 - 12/31/2008 USD ($) USD ($) / shares $TwelveMonthsEnded_31Dec2008http://www.sec.gov/CIK0000065984duration2008-01-01T00:00:002008-12-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDEPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3true0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseWeighted average assumptions used in determining fair values of stock option4false0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.25730.2573falsefalsefalsefalsefalse2truetruefalse0.24390.2439falsefalsefalsefalsefalse3truetruefalse0.1890.189falsefalsefalsefalsefalseOtherus-types:percentItemTypepureThe estimated measure of the percentage amount by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(b) falsefalseStock price volatility5false0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedTermus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse5.465.46falsefalsefalsefalsefalse2truefalsefalse5.335.33falsefalsefalsefalsefalse3truefalsefalse4.644.64falsefalsefalsefalsefalseOtherxbrli:decimalItemTypedecimalThe period of time a share-based award is expected to be outstanding. A share-based award's expected term shall be determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior. An entity is required to aggregate individual awards into relatively homogeneous groups.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(a) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section D -Subsection 2 falsefalseExpected term in years6false0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.02570.0257falsefalsefalsefalsefalse2truetruefalse0.02220.0222falsefalsefalsefalsefalse3truetruefalse0.02770.0277falsefalsefalsefalsefalseOtherus-types:percentItemTypepureThe risk-free interest rate assumption that is used in valuing an option on its own shares.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(d) falsefalseRisk-free interest rate7false0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRateus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truetruefalse0.03740.0374falsefalsefalsefalsefalse2truetruefalse0.03500.0350falsefalsefalsefalsefalse3truetruefalse0.02960.0296falsefalsefalsefalsefalseOtherus-types:percentItemTypepureThe estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(c) falsefalseDividend yield8false0etr_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsDividendPaymentPerShareetrfalsenadurationShare based compensation arrangement by share based payment award fair value assumptions dividend payment per share.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse3.243.24falsetruefalsefalsefalse2truefalsefalse3.003.00falsetruefalsefalsefalse3truefalsefalse3.003.00falsetruefalsefalsefalseEPSxbrli:pureItemTypepureShare based compensation arrangement by share based payment award fair value assumptions dividend payment per share.No authoritative reference available.falsetrueDividend payment per share36Stock-Based Compensation (Details 1) (USD $)UnKnownUnKnownNoRoundingUnKnowntruetrue