Stock Plans 4 (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Stock option awards activity roll-forward
Number of shares, Outstanding beginning balance	5.8	8.0	11.3
Weighted average exercise price, Outstanding beginning balance	$ 23.52	$ 23.03	$ 24.65
Number of shares, Granted	1.8	0.6	1.2
Weighted average exercise price, Granted	$ 24.39	$ 21.89	$ 19.34
Number of shares, Exercised	(1.2)	(1.8)	(0.5)
Weighted average exercise price, Exercised	$ 17.17	$ 20.79	$ 18.81
Number of shares, Expired or terminated	(0.4)	(1.0)	(4.0)
Weighted average exercise price, Expired or terminated	$ 22.09	$ 23.46	$ 27.05
Number of shares, Outstanding ending balance	6.0	5.8	8.0
Weighted average exercise price, Outstanding ending balance	$ 25.17	$ 23.52	$ 23.03
Stock option awards exercisable
Number of shares, Options exercisable	3.7	4.7	6.8
Weighted average exercise price, Options exercisable	$ 26.18	$ 24.24	$ 23.66