|
SHARE-BASED COMPENSATION Option Activity (Details) (USD $)
|
12 Months Ended | |
|---|---|---|
|
Dec. 31, 2014
|
Dec. 31, 2013
|
|
| Non-vested Options | ||
| Outstanding as of December 31, 2013 | 200,556era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedNumberofShares | |
| Forfeited (in shares) | 0era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberofShares | |
| Outstanding as of December 31, 2014 | 77,500era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedNumberofShares | 200,556era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedNumberofShares |
| Nonvested Options | ||
| Outstanding as of December 31, 2013 | $ 10.21era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue | |
| Granted | $ 10.86us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue | $ 9.59us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue |
| Vested | $ 9.36era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue | |
| Forfeited | $ 0.00era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue | |
| Outstanding as of December 31, 2014 | $ 9.54era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue | $ 10.21era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue |
| Vested/Exercisable Options | ||
| Outstanding as of December 31, 2013 | 127,484us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber | |
| Granted (in shares) | 0era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedandExpectedtoVestGrantsinPeriodExercisableNumber | |
| Vested (in shares) | 168,056era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedandExpectedtoVestVestedinPeriodExercisableNumber | |
| Exercised (in shares) | (15,892)era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedandExpectedtoVestExercisesinPeriodExercisableNumber | |
| Expired (in shares) | (15,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod | |
| Forfeited (in shares) | 0era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedandExpectedtoVestForfeituresinPeriodExercisableNumber | |
| Outstanding as of December 31, 2014 | 264,648us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber | 127,484us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber |
| Vested/Exercisable Options | ||
| Outstanding as of December 31, 2013 | $ 16.14us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice | |
| Granted | $ 0.00era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedandExpectedtoVestGrantsinPeriodExercisableWeightedAverageExercisePrice | |
| Vested | $ 22.02era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedandExpectedtoVestVestedinPeriodExercisableWeightedAverageExercisePrice | |
| Exercised | $ 20.15era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedandExpectedtoVestExercisesinPeriodExercisableWeightedAverageExercisePrice | |
| Expired | $ 26.23us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice | |
| Forfeited | $ 0.00era_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsVestedandExpectedtoVestForfeituresinPeriodExercisableWeightedAverageExercisePrice | |
| Outstanding as of December 31, 2014 | $ 19.06us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice | $ 16.14us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice |
| Total Options | ||
| Outstanding as of December 31, 2013 | 328,040us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | |
| Granted (in shares) | 45,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross | |
| Exercised (in shares) | (15,892)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised | |
| Expired (in shares) | (15,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod | |
| Forfeited (in shares) | 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod | |
| Outstanding as of December 31, 2014 | 342,148us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber | 328,040us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber |
| Total Options | ||
| Outstanding as of December 31, 2013 | $ 19.05us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | |
| Granted | $ 29.24us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice | |
| Exercised | $ 20.15us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice | |
| Expired | $ 26.23us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice | |
| Forfeited | $ 0.00us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice | |
| Outstanding as of December 31, 2014 | $ 20.02us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice | $ 19.05us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares No definition available.
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value No definition available.
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercises in Period, Exercisable, Number No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercises in Period, Exercisable, Weighted Average Exercise Price No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Forfeitures in Period, Exercisable, Number No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Forfeitures in Period, Exercisable, Weighted Average Exercise Price No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Grants in Period, Exercisable, Number No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Grants in Period, Exercisable, Weighted Average Exercise Price No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Vested in Period, Exercisable, Number No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Vested in Period, Exercisable, Weighted Average Exercise Price No definition available.
|
| X | ||||||||||
|
- Definition
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value No definition available.
|
| X | ||||||||||
|
- Definition
Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Gross number of share options (or share units) granted during the period. No definition available.
|
| X | ||||||||||
|
- Definition
The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Number of options outstanding, including both vested and non-vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
|
| X | ||||||||||
|
- Definition
Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired. No definition available.
|
| X | ||||||||||
|
- Definition
Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated. No definition available.
|
| X | ||||||||||
|
- Definition
Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options. No definition available.
|
| X | ||||||||||
|
- Definition
Number of share options (or share units) exercised during the current period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|