Common Shares and Stock Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Feb. 29, 2012
Stock option transactions and prices
Granted, Shares
Common shares - Class A [Member]
Stock option transactions and prices
Stock option outstanding at beginning, Shares	4,526,821
Stock option outstanding weighted average Exercise price, Beginning	20.12
Stock option outstanding, weighted-average remaining contractual term, Beginning Balance	6.0
Stock option outstanding, aggregate intrinsic value, Beginning Balance	14,278
Granted, Shares
Granted, Weighted- Average Exercise Price
Exercised, Shares	(682,297)
Exercised, Weighted- Average Exercise Price	23.25
Expired, Shares	(32,391)
Expired, Weighted Average Exercise Price	20.67
Forfeited, Shares	(214,706)
Forfeited, Weighted- Average Exercise Price	24.72
Stock option outstanding Ending, Shares	3,597,427
Stock option outstanding weighted average Exercise price, Ending	20.96
Stock option outstanding, weighted-average remaining contractual term, Ending Balance	5.2
Stock option outstanding, aggregate intrinsic value, Ending Balance	3,375
Exercisable, Shares	3,339,219
Exercisable, weighted- average exercise price	20.69
Exercisable, weighted-average remaining contractual term (in years)	5.2
Exercisable, aggregate intrinsic value	3,375
Common shares - Class B [Member]
Stock option transactions and prices
Stock option outstanding at beginning, Shares	1,166,395
Stock option outstanding weighted average Exercise price, Beginning	19.96
Stock option outstanding, weighted-average remaining contractual term, Beginning Balance	5.7
Stock option outstanding, aggregate intrinsic value, Beginning Balance	2,578
Granted, Shares
Granted, Weighted- Average Exercise Price
Exercised, Shares	(245,250)
Exercised, Weighted- Average Exercise Price	24.60
Expired, Shares	(63,564)
Expired, Weighted Average Exercise Price	22.26
Forfeited, Shares
Forfeited, Weighted- Average Exercise Price
Stock option outstanding Ending, Shares	857,581
Stock option outstanding weighted average Exercise price, Ending	23.06
Stock option outstanding, weighted-average remaining contractual term, Ending Balance	4.7
Stock option outstanding, aggregate intrinsic value, Ending Balance	420
Exercisable, Shares	722,415
Exercisable, weighted- average exercise price	24.11
Exercisable, weighted-average remaining contractual term (in years)	4.5
Exercisable, aggregate intrinsic value