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Track Maintenance Agreement (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2012
Sep. 30, 2012
Dec. 31, 2011
Track Maintenance Agreement (Textual) [Abstract]      
Track maintenance revenue from third party $ 0 $ 0 $ 869
Track maintenance expiration   Dec. 31, 2011