Retirement and Postretirement Benefit Plans - Components of Net Periodic Benefit Cost and Changes Recognized Other Comprehensive Income, Postretirement Benefit Plan (Detail) (Postretirement Benefit Plan [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2013
Postretirement Benefit Plan [Member]
Components of net periodic benefit cost:
Service cost	$ 368	$ 431	$ 684
Interest cost	2,545	2,397	2,841
Expected return on plan assets	(2,882)	(3,067)	(3,430)
Amortization of prior service credit	(1,304)	(1,303)	(2,075)
Amortization of actuarial gain	(1,435)	(1,043)	(452)
Defined benefit plan, net periodic benefit cost, total	(2,708)	(2,585)	(2,432)
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Actuarial gain	(3,818)	(1,659)	(13,768)
Amortization of actuarial gain	1,435	1,043	452
Amortization of prior service credit	1,304	1,303	2,075
Total recognized in other comprehensive income	(1,079)	687	(11,241)
Total recognized in net periodic benefit cost and other comprehensive income	$ (3,787)	$ (1,898)	$ (13,673)