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Stock-Based Compensation (Details) (USD $) | 6 Months Ended | 1 Months Ended
--- | --- | ---
Jun. 30, 2013 | Jun. 30, 2012 | May 31, 2013 Deferred Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Units granted to each grantee (in shares) |  |  | 243
Grant date fair value per grant |  |  | $ 56,250
Expense recognized in connection with the issuance of Deferred Stock Units | $ 394,000 | $ 300,000 | $ 394,000

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