Common And Preferred Stock (Narrative) (Details) (USD $)	12 Months Ended					1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2013 Minimum [Member]	Mar. 31, 2013 Maximum [Member]	Nov. 30, 2009 Two Thousand And Nine Program [Member]	Nov. 30, 2011 Two Thousand And Eleven Program [Member]	Mar. 31, 2013 Common Stock [Member]	Mar. 31, 2012 Common Stock [Member]	Mar. 31, 2013 Series A Junior Participating Preferred Stock [Member]	Mar. 31, 2012 Series A Junior Participating Preferred Stock [Member]	Mar. 31, 2013 Series B 6.75% Convertible Perpetual Preferred Stock [Member]	Mar. 31, 2012 Series B 6.75% Convertible Perpetual Preferred Stock [Member]	Mar. 31, 2011 Series B 6.75% Convertible Perpetual Preferred Stock [Member]	Mar. 31, 2010 Series B 6.75% Convertible Perpetual Preferred Stock [Member]	Mar. 31, 2006 Series B 6.75% Convertible Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized	100,000,000							100,000,000	100,000,000
Stock Repurchase Program, Authorized Amount						$ 150,000,000	$ 100,000,000
Cost of common stock repurchased under share repurchase program	8,631,000	3,488,000	46,696,000			70,000,000
Common stock, shares outstanding	23,343,973							23,343,973	23,257,175
Weighted-average cost per share	$ 50.94	$ 43.49	$ 41.95			$ 44.02
Number of shares repurchased	169,432	80,191	1,113,125			1,589,701
Preferred stock, shares authorized	5,000,000									500,000	500,000	220,000	220,000
Preferred stock, shares issued										0	0	219,999	219,999			220,000
Preferred stock, shares outstanding										0	0	219,999	219,999	220,000	220,000
Dividend common stock				0.43
Preferred stock liquidation price	$ 1,000
Common stock program expiration date						Nov. 01, 2011	Nov. 15, 2013
Series B 6.75% convertible perpetual preferred stock, quarterly dividend rate	6.75%
Preferred stock exceeding percentage on closing price	135.00%
Preferred stock, conversion period				March 15, 2013	March 15, 2018
Preferred stock, conversion rate	21.8475
Preferred shares, conversion price	$ 45.77
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 91,000,000