Supplemental Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accrued liabilities	$ 181,460	$ 137,561
Accrued rebates	28,312	23,758
Management services	400	400	850
Interest income	4,010	2,865	1,510
Franchise taxes	(664)	(893)	(754)
Equity in income of joint ventures	1,444	2,890	2,212
Other	(1,670)	366	653
Other income, net	3,520	5,628	4,471
Interest paid, net of interest capitalized	42,266	48,431	33,980
Income taxes paid	179,882	126,283	108,218
Stated interest rate	6.50%
GO Zone 6 1/2% Senior Notes Due 2029 [Member]
Stated interest rate	6.50%	6.50%
Maturity date	2029
6 1/2% Tax-Exempt Revenue Bonds Due 2029 [Member]
Proceeds from borrowings related to revenue bonds (in restricted cash)	0	0	93,943
GO Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]
Proceeds from borrowings related to revenue bonds (in restricted cash)	0	0	87,940
Stated interest rate	6.50%	6.50%
Maturity date	2035
IKE Zone 6 1/2% Tax-Exempt Revenue Bonds Due 2035 [Member]
Proceeds from borrowings related to revenue bonds (in restricted cash)	$ 0	$ 0	$ 64,209
Stated interest rate	6.50%	6.50%
Maturity date	2035