Retirement and Postretirement Benefit Plans (Details 5) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Feb. 29, 2012	Feb. 28, 2011	Feb. 28, 2010
Pension Plans [Member]
Components of periodic benefit cost for defined benefit pension and postretirement benefit plans
Service cost	$ 1,106	$ 957	$ 730
Interest cost	8,353	8,757	9,279
Expected return on plan assets	(6,858)	(6,588)	(5,637)
Amortization of transition obligation	6	6	6
Amortization of prior service cost	240	178	261
Amortization of actuarial (gain) loss	2,126	133	1,942
Settlements		(3)	126
Net periodic benefit cost	4,973	3,440	6,707
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Actuarial loss/gain	14,996	1,175	6,069
Prior service cost	924	198	53
Amortization of prior service cost	(240)	(178)	(261)
Amortization of actuarial loss (gain)	(2,126)	(133)	(1,942)
Amortization of transition obligation	(6)	(6)	(6)
Settlements		3	(126)
Total recognized in other comprehensive income	13,548	1,059	3,787
Total recognized in net periodic benefit cost and other comprehensive income	18,521	4,499	10,494
Postretirement benefit plan [Member]
Components of periodic benefit cost for defined benefit pension and postretirement benefit plans
Service cost	726	2,290	2,365
Interest cost	3,929	6,014	7,359
Expected return on plan assets	(4,310)	(4,503)	(4,107)
Amortization of prior service cost	(2,461)	(7,712)	(7,418)
Amortization of actuarial (gain) loss	(766)	1,078	2,386
Net periodic benefit cost	(2,882)	(2,833)	585
Other changes in plan assets and benefit obligations recognized in other comprehensive income:
Actuarial loss/gain	(5,115)	(21,265)	(21,723)
Prior service cost		(7,263)
Amortization of prior service cost	2,461	7,712	7,418
Amortization of actuarial loss (gain)	766	(1,078)	(2,386)
Total recognized in other comprehensive income	(1,888)	(21,894)	(16,691)
Total recognized in net periodic benefit cost and other comprehensive income	$ (4,770)	$ (24,727)	$ (16,106)