Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Property, plant and equipment
Land	$ 1,432	$ 1,432
Building improvements	535,911	520,137
Machinery and equipment	260,620	246,584
Capitalized leases for machinery, equipment and buildings	77,435	76,244
Property, plant and equipment, gross	875,398	844,397
Accumulated depreciation and amortization	(253,551)	(235,528)
Property Plant and Equipment Net before Construction in Progress	621,847	608,869
Construction in Progress	71,722	78,807
Property, plant and equipment, net	$ 693,569	$ 687,676