Retirement and Postretirement Benefit Plans - Components of Net Periodic Benefit Cost and Changes Recognized Other Comprehensive Income, Postretirement Benefit Plan (Detail) (Postretirement Benefits Plans [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Feb. 29, 2012
Postretirement Benefits Plans [Member]
Components of net periodic benefit cost:
Service cost	$ 431	$ 684	$ 726
Interest cost	2,397	2,841	3,929
Expected return on plan assets	(3,067)	(3,430)	(4,310)
Amortization of prior service credit	(1,303)	(2,075)	(2,461)
Amortization of actuarial gain	(1,043)	(452)	(766)
Net periodic benefit cost	(2,585)	(2,432)	(2,882)
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Actuarial gain	(1,659)	(13,768)	(5,115)
Prior service credit added during the year
Amortization of actuarial gain	1,043	452	766
Amortization of prior service credit	1,303	2,075	2,461
Total recognized in other comprehensive income	687	(11,241)	(1,888)
Total recognized in net periodic benefit cost and other comprehensive income	$ (1,898)	$ (13,673)	$ (4,770)