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Commitments and Contingencies (Schedule of Change in Asset Retirement Obligation) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Balance at beginning of period $ 501 $ 773
Adjustment due to re-estimate 0 (319)
Accretion expense 34 47
Balance at end of period $ 535 $ 501