Property, Plant and Equipment Depreciation Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Property, Plant and Equipment [Abstract]
Cost of sales	$ 90,805	$ 81,891	$ 179,973	$ 161,988
Selling, general and administrative	3,860	5,289	7,995	10,396
Research and development	3,114	2,697	6,109	4,777
Total depreciation expense	$ 97,779	$ 89,877	$ 194,077	$ 177,161