Retirement Benefits - Components of Periodic Benefit Cost for Corporation's Defined Benefit Pension and Postretirement Benefits Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Aug. 26, 2016	Aug. 28, 2015	Aug. 26, 2016	Aug. 28, 2015
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 219	$ 159	$ 405	$ 318
Interest cost	1,588	1,550	3,181	3,108
Expected return on plan assets	(1,500)	(1,659)	(3,028)	(3,327)
Amortization of prior service cost (credit)	1	1	2	2
Amortization of actuarial loss (gain)	904	846	1,777	1,694
Defined benefit plan, net periodic benefit cost, total	1,212	897	2,337	1,795
Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	86	125	172	250
Interest cost	527	525	1,055	1,050
Expected return on plan assets	(582)	(675)	(1,164)	(1,350)
Amortization of prior service cost (credit)	(174)	(175)	(349)	(350)
Amortization of actuarial loss (gain)	(367)	(300)	(734)	(600)
Defined benefit plan, net periodic benefit cost, total	$ (510)	$ (500)	$ (1,020)	$ (1,000)