Retirement Benefits (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Aug. 24, 2012	Aug. 26, 2011	Aug. 24, 2012	Aug. 26, 2011
Defined Benefit Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 333	$ 211	$ 667	$ 415
Interest cost	1,839	2,145	3,683	4,291
Expected return on plan assets	(1,609)	(1,671)	(3,222)	(3,343)
Amortization of prior service cost	62	64	123	123
Amortization of actuarial loss	815	558	1,631	1,127
Net periodic benefit cost	1,440	1,307	2,882	2,613
Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	212	362	425	725
Interest cost	800	1,210	1,600	2,420
Expected return on plan assets	(840)	(1,097)	(1,680)	(2,195)
Amortization of prior service cost	(519)	(637)	(1,038)	(1,275)
Net periodic benefit cost	$ (347)	$ (162)	$ (693)	$ (325)