Retirement and Postretirement Benefit Plans - Components of Net Periodic Benefit Cost and Changes Recognized Other Comprehensive Income, Postretirement Benefit Plan (Detail) (Postretirement Benefit Plans [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Feb. 28, 2013	Feb. 29, 2012	Feb. 28, 2011
Postretirement Benefit Plans [Member]
Components of net periodic benefit cost:
Service cost	$ 684	$ 726	$ 2,290
Interest cost	2,841	3,929	6,014
Expected return on plan assets	(3,430)	(4,310)	(4,503)
Amortization of prior service credit	(2,075)	(2,461)	(7,712)
Amortization of actuarial (gain) loss	(452)	(766)	1,078
Net periodic benefit cost	(2,432)	(2,882)	(2,833)
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Actuarial gain	(13,768)	(5,115)	(21,265)
Prior service credit added during the year			(7,263)
Amortization of actuarial gain (loss)	452	766	(1,078)
Amortization of prior service credit	2,075	2,461	7,712
Total recognized in other comprehensive income	(11,241)	(1,888)	(21,894)
Total recognized in net periodic benefit cost and other comprehensive income	$ (13,673)	$ (4,770)	$ (24,727)