Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 306,818	$ 528,027	$ 757,175	$ 361,954	$ 270,422	$ 503,584	$ 706,423	$ 312,889	$ 1,953,974	$ 1,793,318	$ 1,613,746
Gross profit	88,938	151,501	222,405	104,563	80,835	147,906	211,439	91,410	567,407	531,590	471,262
Net income (loss)	$ (7,997)	$ 21,375	$ 64,943	$ 3,651	$ (10,115)	$ 24,169	$ 58,577	$ (638)	$ 81,972	$ 71,993	$ 57,638
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.17)	$ 0.46	$ 1.38	$ 0.08	$ (0.21)	$ 0.50	$ 1.21	$ (0.01)	$ 1.75	$ 1.49	$ 1.17
Diluted (in dollars per share)	$ (0.17)	$ 0.45	$ 1.34	$ 0.08	$ (0.21)	$ 0.50	$ 1.19	$ (0.01)	$ 1.71	$ 1.47	$ 1.15