Line of Credit - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			3 Months Ended					1 Months Ended	12 Months Ended	1 Months Ended
	Jan. 31, 2013	Oct. 31, 2012	Nov. 30, 2010	Jan. 31, 2013 Forward starting swaps	Jan. 31, 2013 Interest Rate Swap	Oct. 31, 2012 Interest Rate Swap	Jan. 31, 2013 Standby Letters of Credit	Jan. 31, 2013 Swing Line Loan	Nov. 30, 2010 Second Amendment	Oct. 31, 2011 Second Amendment	Nov. 30, 2010 Second Amendment Minimum	Nov. 30, 2010 Second Amendment Maximum	Nov. 30, 2010 Second Amendment Federal Funds Rate	Nov. 30, 2010 Second Amendment Eurodollar Rate	Nov. 30, 2010 Second Amendment Base Rate Loans Minimum	Nov. 30, 2010 Second Amendment Base Rate Loans Maximum	Nov. 30, 2010 Second Amendment Eurodollar Loans Minimum	Nov. 30, 2010 Second Amendment Eurodollar Loans Maximum	Jan. 31, 2013 Unrealized Loss On Derivatives
Line of Credit Facility [Line Items]
Terminated existing line of credit borrowing capacity			$ 450.0
Line of credit, maximum borrowing capacity			650.0				300.0	50.0
Syndicated line of credit facility, expiration date										Sep. 08, 2016
Syndicated line of credit, optional maximum capacity at any time prior to the expiration (subject to receipt of commitments for the increased amount from existing and new lenders)			850.0
Variable rate													0.50%	1.00%	0.00%	0.75%	1.00%	1.75%
Percentage of commitment fee on the unused portion of the Facility											0.225%	0.30%
Line of credit, interest rate terms									Borrowings under the Facility bear interest at a rate equal to an applicable margin plus, at the Company’s option, either a (a) eurodollar rate (generally LIBOR) or (b) base rate determined by reference to the highest of (1) the federal funds rate plus 0.50%, (2) the prime rate announced by Bank of America, N.A. from time to time, and (3) the eurodollar rate plus 1.00%. The applicable margin is a percentage per annum varying from 0.00% to 0.75% for base rate loans and 1.00% to 1.75% for eurodollar loans, based upon the Company’s leverage ratio. The Company also pays a commitment fee, based on the leverage ratio, payable quarterly in arrears, ranging from 0.225% to 0.300% on the average daily unused portion of the Facility. For purposes of this calculation, irrevocable standby letters of credit, issued primarily in conjunction with the Company’s self-insurance program, and cash borrowings are included as outstanding under the Facility.
Description of covenants under the Facility	The Credit Agreement contains certain leverage and liquidity covenants that require us to maintain a maximum leverage ratio of 3.25x at the end of each fiscal quarter, a minimum fixed charge coverage ratio of 1.50x at any time, and a consolidated net worth in an amount not less than the sum of (i) $570.0 million, (ii) 50% of our consolidated net income (with no deduction for net loss), and (iii) 100% of our aggregate increases in stockholder’s equity, beginning on November 30, 2010, each as further described in the Credit Agreement, as amended. The Company was in compliance with all covenants as of January 31, 2013.
Covenants maximum leverage ratio	3.25
Minimum fixed charge coverage ratio	1.50
Consolidated net worth	570.0
Consolidated net income earned	50.00%
Aggregate increases in stockholders' equity	100.00%
Line of credit, amount outstanding	423.0	104.0
Standby letters of credit under the credit facility	215.0	105.0
Line of credit, borrowing capacity currently available	123.0	330.0
Derivative agreement date				Oct. 19, 2010
Description of derivative agreement				The Company entered into a three-year forward starting interest rate swap agreement with an underlying notional amount of $25.0 million, pursuant to which the Company receives variable interest payments based on LIBOR and pays fixed interest at a rate of 0.89%. The effective date of this hedge was February 24, 2011. This swap is intended to hedge the interest risk associated with the Company's forecasted floating-rate, LIBOR-based debt.
Interest rate swap agreement period				3 years
Notional amount of derivatives				25.0
Derivative, fixed interest rate				0.89%
Derivative, effective date				Feb. 24, 2011
Derivative, maturity date				Feb. 24, 2014
Fair value of interest rate swaps					0.2	0.2
Effective portion of cash flow hedges included in accumulated other comprehensive loss, before tax					0.2	0.2
Effective portion of cash flow hedges included in accumulated other comprehensive loss, net of tax					0.1	0.1
Unrealized net losses related to the interest rate swap contract																			$ 0.2