Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Property, plant and equipment
Land	$ 1,415	$ 1,432
Building improvements	559,732	520,137
Machinery and equipment	270,659	246,584
Capitalized leases for machinery, equipment and buildings	76,195	76,244
Property, plant and equipment, gross	908,001	844,397
Accumulated depreciation and amortization	(272,590)	(235,528)
Property Plant and Equipment Net before Construction in Progress	635,411	608,869
Construction in Progress	57,615	78,807
Property, plant and equipment, net	$ 693,026	$ 687,676