Share-Based Compensation (Summary of Stock Option Activity) (Details)	3 Months Ended
	Jun. 30, 2018 shares
Number of Options
Beginning balance (in shares)	3,549,405
Granted (in shares)	1,258,340
Exercised (in shares)	(16,218)
Forfeited (in shares)	(11,800)
Ending balance (in shares)	4,779,727
Options vested and expected to vest (in shares)	4,779,727
Options exercisable (in shares)	798,921