Restatement (Details) (USD $) In Thousands	Aug. 26, 2011	Feb. 28, 2011	Aug. 27, 2010
The impact of restatement in the Corporation's consolidated
Deferred and refundable income taxes	$ 59,876	$ 64,898	$ 76,589
Total current assets	745,578	715,771	616,019
Total assets	1,586,139	1,547,249	1,451,814
Retained earnings	1,214,008	1,185,855	1,150,877
Total shareholders' equity	799,623	763,758	690,475
As Previously [Member]
The impact of restatement in the Corporation's consolidated
Deferred and refundable income taxes	45,029	50,051	61,742
Total current assets	730,731	700,924	601,173
Total assets	1,571,293	1,532,402	1,436,967
Retained earnings	1,199,161	1,171,008	1,136,031
Total shareholders' equity	784,776	748,911	675,629
As Restated [Member]
The impact of restatement in the Corporation's consolidated
Deferred and refundable income taxes	59,876	64,898	76,589
Total current assets	745,578	715,771	616,019
Total assets	1,586,139	1,547,249	1,451,814
Retained earnings	1,214,008	1,185,855	1,150,877
Total shareholders' equity	$ 799,623	$ 763,758	$ 690,475