Stock Plans 5 (Details) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Mar. 31, 2017 USD ($) $ / shares shares
Summary of stock option information by exercise price range
Shares, Options outstanding | shares	3.8
Aggregate intrinsic value, Options outstanding | $	$ 11.2
Weighted average remaining contractual life, Options outstanding (in years)	7 years 6 months
Weighted average exercise price, Options outstanding (in dollars per share)	$ 28.88
Shares, Options exercisable | shares	2.1
Aggregate intrinsic value, Options exercisable | $	$ 9.9
Weighted average remaining contractual life, Options exercisable (in years)	6 years 6 months
Weighted average exercise price, Options exercisable (in dollars per share)	$ 27.09
Exercise Price Range $22.82 - $25.00
Summary of stock option information by exercise price range
Range of exercise prices, Minimum (in dollars per share)	22.82
Range of exercise prices, Maximum (in dollars per share)	$ 25.00
Shares, Options outstanding | shares	0.7
Aggregate intrinsic value, Options outstanding | $	$ 5.6
Weighted average remaining contractual life, Options outstanding (in years)	5 years 9 months 18 days
Weighted average exercise price, Options outstanding (in dollars per share)	$ 23.50
Shares, Options exercisable | shares	0.7
Aggregate intrinsic value, Options exercisable | $	$ 5.6
Weighted average remaining contractual life, Options exercisable (in years)	5 years 9 months 18 days
Weighted average exercise price, Options exercisable (in dollars per share)	$ 23.50
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 | shares	0.9
Aggregate intrinsic value, Options outstanding | $	$ 3.8
Weighted average remaining contractual life, Options outstanding (in years)	6 years 7 months 6 days
Weighted average exercise price, Options outstanding (in dollars per share)	$ 27.76
Shares, Options exercisable | shares	0.8
Aggregate intrinsic value, Options exercisable | $	$ 3.4
Weighted average remaining contractual life, Options exercisable (in years)	6 years 6 months
Weighted average exercise price, Options exercisable (in dollars per share)	$ 27.53
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 | shares	2.2
Aggregate intrinsic value, Options outstanding | $	$ 1.8
Weighted average remaining contractual life, Options outstanding (in years)	8 years 3 months 18 days
Weighted average exercise price, Options outstanding (in dollars per share)	$ 31.07
Shares, Options exercisable | shares	0.6
Aggregate intrinsic value, Options exercisable | $	$ 0.9
Weighted average remaining contractual life, Options exercisable (in years)	7 years 3 months 18 days
Weighted average exercise price, Options exercisable (in dollars per share)	$ 30.34