Stock Plans 5 (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2015
Summary of stock option information by exercise price range
Shares, Options outstanding	3.2
Aggregate intrinsic value, Options outstanding	$ 17.6
Weighted average remaining contractual life, Options outstanding (in years)	7 years 6 months 0 days
Weighted average exercise price, Options outstanding (in dollars per share)	$ 27.02
Shares, Options exercisable	1.2
Aggregate intrinsic value, Options exercisable	7.8
Weighted average remaining contractual life, Options exercisable (in years)	6 years 8 months 12 days
Weighted average exercise price, Options exercisable (in dollars per share)	$ 25.92
Exercise Price Range $19.93 - $25.00
Summary of stock option information by exercise price range
Range of exercise prices, Minimum (in dollars per share)	$ 19.93
Range of exercise prices, Maximum (in dollars per share)	$ 25.00
Shares, Options outstanding	0.9
Aggregate intrinsic value, Options outstanding	7.9
Weighted average remaining contractual life, Options outstanding (in years)	6 years 9 months 18 days
Weighted average exercise price, Options outstanding (in dollars per share)	$ 23.56
Shares, Options exercisable	0.6
Aggregate intrinsic value, Options exercisable	5.2
Weighted average remaining contractual life, Options exercisable (in years)	7 years 0 months 0 days
Weighted average exercise price, Options exercisable (in dollars per share)	$ 23.46
Exercise Price Range $25.01 - $30.00
Summary of stock option information by exercise price range
Range of exercise prices, Minimum (in dollars per share)	$ 25.01
Range of exercise prices, Maximum (in dollars per share)	$ 30.00
Shares, Options outstanding	1.5
Aggregate intrinsic value, Options outstanding	8.1
Weighted average remaining contractual life, Options outstanding (in years)	7 years 8 months 12 days
Weighted average exercise price, Options outstanding (in dollars per share)	$ 27.31
Shares, Options exercisable	0.4
Aggregate intrinsic value, Options exercisable	2.2
Weighted average remaining contractual life, Options exercisable (in years)	6 years 10 months 24 days
Weighted average exercise price, Options exercisable (in dollars per share)	$ 26.50
Exercise Price Range $30.01 - over
Summary of stock option information by exercise price range
Range of exercise prices, Minimum (in dollars per share)	$ 30.01
Shares, Options outstanding	0.8
Aggregate intrinsic value, Options outstanding	1.6
Weighted average remaining contractual life, Options outstanding (in years)	7 years 10 months 24 days
Weighted average exercise price, Options outstanding (in dollars per share)	$ 30.52
Shares, Options exercisable	0.2
Aggregate intrinsic value, Options exercisable	$ 0.4
Weighted average remaining contractual life, Options exercisable (in years)	5 years 7 months 6 days
Weighted average exercise price, Options exercisable (in dollars per share)	$ 31.05