Retirement Benefits (Details) (USD $)				3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended
	Aug. 26, 2011	Feb. 28, 2011	Aug. 27, 2010	Aug. 26, 2011 Defined Benefit Pension [Member]	Aug. 27, 2010 Defined Benefit Pension [Member]	Aug. 26, 2011 Defined Benefit Pension [Member]	Aug. 27, 2010 Defined Benefit Pension [Member]	Aug. 26, 2011 Postretirement Benefit [Member]	Aug. 27, 2010 Postretirement Benefit [Member]	Aug. 26, 2011 Postretirement Benefit [Member]	Aug. 27, 2010 Postretirement Benefit [Member]	Aug. 26, 2011 Profit Sharing [Member]	Aug. 27, 2010 Profit Sharing [Member]	Aug. 26, 2011 401(k) [Member]	Aug. 27, 2010 401(k) [Member]	Aug. 26, 2011 401(k) [Member]	Aug. 27, 2010 401(k) [Member]
Components of periodic benefit cost for defined benefit pension and postretirement benefit plans
Service cost				$ 211,000	$ 250,000	$ 415,000	$ 501,000	$ 362,000	$ 575,000	$ 725,000	$ 1,150,000
Interest cost				2,145,000	2,206,000	4,291,000	4,418,000	1,210,000	1,550,000	2,420,000	3,100,000
Expected return on plan assets				(1,671,000)	(1,654,000)	(3,343,000)	(3,314,000)	(1,097,000)	(1,125,000)	(2,195,000)	(2,250,000)
Amortization of prior service cost (credit)				64,000	44,000	123,000	88,000	(637,000)	(1,850,000)	(1,275,000)	(3,700,000)
Amortization of actuarial loss				558,000	524,000	1,127,000	1,050,000		250,000		500,000
Net periodic benefit cost				1,307,000	1,370,000	2,613,000	2,743,000	(162,000)	(600,000)	(325,000)	(1,200,000)
Retirement Benefits (Textuals) [Abstract]
Profit sharing plan expense recognized during the period												5,200,000	4,500,000	1,200,000	1,000,000	2,600,000	2,100,000
Liability for postretirement benefits other than pensions	27,900,000	24,100,000	49,200,000
Long-term liability for pension benefits	$ 60,000,000	$ 60,100,000	$ 58,900,000