Share-Based Compensation (Summary of Stock Option Activity) (Details)	6 Months Ended
	Sep. 30, 2018 shares
Number of Options
Beginning balance (in shares)	3,549,405
Granted (in shares)	1,710,760
Exercised (in shares)	(73,989)
Forfeited (in shares)	(70,682)
Ending balance (in shares)	5,115,494
Options vested and expected to vest (in shares)	5,115,494
Options exercisable (in shares)	1,195,945