Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Asset write-down	$ 5,498	$ 450	$ 8,580	$ 2,928
Spare Parts Sales [Member]
Prior Period Reclassification Adjustment		2,800		4,200
Cost Of Spare Parts Sales [Member]
Prior Period Reclassification Adjustment		$ 2,800		$ 4,200