Property, Plant and Equipment (Details Textuals) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment
Depreciation expense	$ 214,899,000	$ 179,905,000	$ 133,360,000
Accounts payable for purchases of property and equipment	$ 24,400,000	$ 32,700,000	$ 18,100,000