Retirement Benefits - Components of Periodic Benefit Cost for Corporation's Defined Benefit Pension and Postretirement Benefits Plans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	May 31, 2013	May 25, 2012
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 320	$ 334
Interest cost	1,742	1,844
Expected return on plan assets	(1,574)	(1,613)
Amortization of prior service cost (credit)	51	61
Amortization of actuarial loss (gain)	917	816
Defined Benefit Plan, Net Periodic Benefit Cost, Total	1,456	1,442
Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	138	213
Interest cost	613	800
Expected return on plan assets	(763)	(840)
Amortization of prior service cost (credit)	(325)	(519)
Amortization of actuarial loss (gain)	(213)
Defined Benefit Plan, Net Periodic Benefit Cost, Total	$ (550)	$ (346)