Long-Term Debt - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended		12 Months Ended									1 Months Ended			1 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended				1 Months Ended
	Nov. 30, 2010	Jun. 30, 2008	Feb. 29, 2012	Feb. 28, 2011	Nov. 30, 2010	Nov. 30, 2011	Feb. 28, 2009	Nov. 30, 2010 LIBOR Minimum	Nov. 30, 2010 LIBOR Maximum	Feb. 29, 2012 5.4 percent Senior Notes	Nov. 30, 2011 5.4 percent Senior Notes	Nov. 30, 2010 Senior Notes Due April 2009	Jun. 30, 2008 Senior Notes Due April 2009	Jan. 31, 2011 4.6 percent Senior Notes	Feb. 29, 2012 4.6 percent Senior Notes	Nov. 30, 2011 4.6 percent Senior Notes	Jan. 31, 2011 4.6 percent Senior Notes Semi Annual Payment, First Payment	Jan. 31, 2011 4.6 percent Senior Notes Semi Annual Payment, Second Payment	Feb. 29, 2012 4.8 percent Revenue Bonds	Nov. 30, 2011 4.8 percent Revenue Bonds	Feb. 29, 2012 6.3 percent Term Loan Year	Nov. 30, 2011 6.3 percent Term Loan	Feb. 29, 2012 TIF bond debt service funding commitment	Nov. 30, 2011 TIF bond debt service funding commitment	Feb. 29, 2012 TIF bond debt service funding commitment Semi Annual Payment, First Payment	Feb. 29, 2012 TIF bond debt service funding commitment Semi Annual Payment, Second Payment	Feb. 29, 2012 TIF bond debt service funding commitment Term Bond Due December 1st 2017	Feb. 29, 2012 TIF bond debt service funding commitment Term Bond Due December 1st 2027	Mar. 31, 2012 Repayment of Debt	Mar. 31, 2012 Repayment of Debt 5.4 percent Senior Notes
Debt Disclosure [Line Items]
Debt term																					25
Proceeds from long-term debt				$ 65,000,000										$ 65,000,000
Debt issuance amount													150,000,000
Debt outstanding amount												65,000,000
Debt, due date										2014-04			2009-04	2021-01							2034-10
Debt, interest rate										5.40%	5.40%			4.60%	4.60%	4.60%			4.80%	4.80%	6.30%	6.30%					6.20%	6.80%
Debt, monthly payment																			29,000		292,000
Frequency of periodic payment														Semi-annual
Long-term debt			346,015,000			316,152,000				87,026,000	87,024,000				65,000,000	65,000,000			1,191,000	1,262,000	50,581,000	50,667,000	62,217,000	62,199,000			13,200,000	49,700,000
Debt, maturity date																											Dec. 01, 2017	Dec. 01, 2027
Early redemption of debt																														87,000,000
Payment of redemption premium																														9,000,000
Loss on early redemption of debt																													(9,100,000)
Notional amount of interest rate swap agreement		150,000,000
Reason for entering into/discontinuation of interest rate swap		To effectively lock in a substantial portion of the interest rate exposure on approximately $150.0 million notional amount in anticipation of refinancing the $150.0 million of senior notes that matured in April 2009			Reduction in the anticipated debt issuance from $150.0 million to $65.0 million
Interest rate swap expiration							2011-02
Deferred in other comprehensive loss associated with interest rate swap being amortized as interest expense over life of the private placement completed in January 2011			5,800,000
Interest rate swap expense expected to be recognized during the next 12 months			(700,000)
Interest payment date																	January 18	July 18							April 1	October 1
Principal payment date																							October 1
2010 Credit Facility	November 2010
2010 Credit Facility current borrowing capacity	300,000,000				300,000,000
2010 Credit Facility potential borrowing capacity	500,000,000				500,000,000
Termination of revolving credit facility	November 2015
2010 Credit Facility interest rate description	Accrues interest at LIBOR plus 150.0 - 225.0 basis points, depending on the better of its debt rating as determined by specified rating agencies or the Company's leverage ratio.
2010 Credit Facility amount outstanding			80,000,000
Debt instrument basis points								1.50%	2.25%
Interest expense			3,437,000	3,842,000
Interest capitalized			1,400,000	600,000
Financing costs deferred			$ 4,700,000			$ 4,900,000