Export Sales and Major Customers (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 335,451	$ 342,170	$ 350,599	$ 317,703	$ 346,142	$ 314,519	$ 337,726	$ 296,190	$ 1,345,923	$ 1,294,577	$ 1,125,295
Revenue, Major Customer [Line Items]
Revenue from major customer, percentage (in hundredths)									71.00%	74.00%	78.00%
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									1,035,090	1,084,131	1,020,722
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									146,623	102,106	72,955
Mexico and South America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									131,240	93,855	0
East Asia and Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 32,970	$ 14,485	$ 31,618