Capital Stock (Details 2) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
SHARES EXCHANGEABLE INTO COMMON STOCK
Dividends Declared per Share (in dollars per share)	$ 0.44	$ 0.32	$ 0.20
Dividends declared but not paid (in dollars)	$ 14,185	$ 11,493	$ 8,990
COMMON STOCK
COMMON STOCK
Beginning balance	139,874,000	150,219,000	161,439,000
Shares issued for:
Stock option exercises and other stock-based compensation	80,000	172,000	638,000
Deferred compensation trust	71,000	68,000	75,000
Deferred compensation	1,925,000	1,246,000	1,520,000
Exchangeable shares	0	0	1,099,000
Shares repurchased and retired	(16,199,000)	(13,597,000)	(14,552,000)
Net share transactions	(410,000)	(64,000)	0
Equity Units exchange	0	1,830,000	0
Ending balance	125,341,000	139,874,000	150,219,000
SHARES EXCHANGEABLE INTO COMMON STOCK
SHARES EXCHANGEABLE INTO COMMON STOCK
Beginning balance	0	0	1,099,000
Exchanges	0	0	(1,099,000)
Ending balance	0	0	0