Long-Lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Property, plant and equipment
Property, plant and equipment	$ 887,861		$ 887,861		$ 843,589
Less accumulated depreciation and amortization	(317,194)		(317,194)		(277,633)
Total property, plant and equipment, net	570,667		570,667		$ 565,956
Depreciation expense	$ 21,300	$ 18,200	$ 42,000	$ 36,200