Stock Plans 8 (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Restricted Stock Awards [Member]
Summary of RSA and RSU activity under the Plans
Number of shares, Outstanding beginning balance	5.7	5.8	5.3
Weighted average grant date fair value, Outstanding beginning balance	$ 22.41	$ 20.56	$ 20.73
Number of shares, RSA / RSU granted	3.5	3.8	4.7
Weighted average grant date fair value, RSA / RSU granted	$ 26.21	$ 24.54	$ 21.41
Number of shares, RSA / RSU released	(3.6)	(3.0)	(3.3)
Weighted average grant date fair value, RSA / RSU released	$ 22.22	$ 21.57	$ 22.00
Number of shares, RSA / RSU forfeitures	(0.6)	(0.9)	(0.9)
Weighted average grant date fair value, RSA / RSU forfeitures	$ 24.69	$ 22.33	$ 20.72
Number of shares, Outstanding ending balance	5.0	5.7	5.8
Weighted average grant date fair value, Outstanding ending balance	$ 24.98	$ 22.41	$ 20.56
Restricted Stock Units [Member]
Summary of RSA and RSU activity under the Plans
Number of shares, Outstanding beginning balance	1.2	1.0	0.9
Weighted average grant date fair value, Outstanding beginning balance	$ 21.91	$ 20.03	$ 20.51
Number of shares, RSA / RSU granted	0.9	0.7	0.6
Weighted average grant date fair value, RSA / RSU granted	$ 23.72	$ 24.06	$ 21.30
Number of shares, RSA / RSU released	(0.6)	(0.3)	(0.4)
Weighted average grant date fair value, RSA / RSU released	$ 21.03	$ 20.70	$ 23.47
Number of shares, RSA / RSU forfeitures	(0.1)	(0.2)	(0.1)
Weighted average grant date fair value, RSA / RSU forfeitures	$ 23.38	$ 21.61	$ 19.05
Number of shares, Outstanding ending balance	1.4	1.2	1.0
Weighted average grant date fair value, Outstanding ending balance	$ 23.28	$ 21.91	$ 20.03