Annual report pursuant to Section 13 and 15(d)

COMMON STOCK Narrative (Details)

v2.4.1.9
COMMON STOCK Narrative (Details) (USD $)
0 Months Ended
Jan. 31, 2013
Aug. 01, 2011
vote
Jul. 31, 2011
Class of Stock [Line Items]      
Common stock, par value $ 0.01us-gaap_CommonStockParOrStatedValuePerShare    
Common stock issued (in shares) 19,883,583us-gaap_StockIssuedDuringPeriodSharesNewIssues    
Common Class A [Member]      
Class of Stock [Line Items]      
Common stock, shares authorized     60,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Common stock, par value     $ 0.01us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
Number of votes per share   1era_CommonStockNumberofVotesperShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember
 
Common Class B [Member]      
Class of Stock [Line Items]      
Common stock, shares authorized     60,000,000us-gaap_CommonStockSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
Common stock, par value     $ 0.01us-gaap_CommonStockParOrStatedValuePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
Common stock issued (in shares)   24,500us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
 
Number of votes per share   8era_CommonStockNumberofVotesperShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember
 
Shares owned by affiliates percent minimum for conversion   20.00%era_CommonStockConvertibleFeatureSharesOwnedbyAffiliatesMinimumforConversionPercent
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassBMember