Stock-based Compensation (Narrative) (Details) $ in Millions	9 Months Ended
	Dec. 31, 2016 USD ($)
Stock-Based Awards
Unamortized stock-based compensation expense related to unvested stock awards	$ 49.7
Weighted average period of recognition for unrecognized compensation costs (in years)	2 years 43 days
Acquisition-related
Unamortized stock-based compensation expense related to unvested stock awards	$ 1.5
Weighted average period of recognition for unrecognized compensation costs (in years)	2 years 151 days
Employee Stock Purchase Plan
Unamortized stock-based compensation expense related to unvested stock awards	$ 0.2
Weighted average period of recognition for unrecognized compensation costs (in years)	72 days