Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Property, plant and equipment
Land	$ 1,888	$ 2,010
Building improvements	593,989	581,286
Machinery and equipment	379,912	360,199
Capitalized leases for machinery, equipment and buildings	22,445	35,129
Property, plant and equipment, gross	998,234	978,624
Accumulated depreciation and amortization	(353,533)	(313,067)
Property Plant and Equipment Net before Construction in Progress	644,701	665,557
Construction in Progress	15,632	18,303
Property, plant and equipment, net	$ 660,333	$ 683,860