Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 340,789	$ 578,157	$ 790,392	$ 370,362	$ 306,818	$ 528,027	$ 757,175	$ 361,954	$ 2,079,700	$ 1,953,974	$ 1,793,318
Gross profit	95,793	162,557	228,166	104,761	88,938	151,501	222,405	104,563	591,277	567,407	531,590
Net income (loss)	$ (4,975)	$ 32,332	$ 66,533	$ 3,440	$ (7,997)	$ 21,375	$ 64,943	$ 3,651	$ 97,330	$ 81,972	$ 71,993
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.11)	$ 0.70	$ 1.43	$ 0.07	$ (0.17)	$ 0.46	$ 1.38	$ 0.08	$ 2.10	$ 1.75	$ 1.49
Diluted (in dollars per share)	$ (0.11)	$ 0.68	$ 1.39	$ 0.07	$ (0.17)	$ 0.45	$ 1.34	$ 0.08	$ 2.05	$ 1.71	$ 1.47