Debt and Credit Arrangements (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 25, 2011	Dec. 26, 2010 Contract	Dec. 27, 2009	Dec. 25, 2011 Amended Credit Facility [Member]	Dec. 26, 2010 New Credit Facility [Member]	Jun. 27, 2010 Old Credit Facility [Member]	Dec. 25, 2011 0.53% Interest Rate Swap Agreements [Member] Contract	Dec. 26, 2010 4.98% Interest Rate Swap Agreements [Member]	Dec. 26, 2010 3.74% Interest Rate Swap Agreements [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 175.0	$ 175.0	$ 175.0
Line of credit facility, term				5 years	5 years
Interest margin rate on debt, minimum				0.75%	1.00%	0.50%
Interest margin rate on debt, maximum				1.50%	1.75%	1.00%
Line of credit facility, remaining borrowing capacity, after reduction for outstanding letters of credit				109.5
Line of credit facility initiation date				November 2011	September 2010
Line of credit facility, maturity date				Nov. 30, 2016
Derivative, fixed interest rate							0.53%	4.98%	3.74%
Floating rate debt							50.0	50.0	50.0
Number of interest rate derivatives held		2					1
Weighted average interest rate for credit facility borrowings, including the impact of interest rate swaps	1.90%	5.20%	4.80%
Interest paid	$ 1.6	$ 5.4	$ 5.5