CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 200,563	$ 154,022	$ 562,351	$ 419,313
Costs and expenses:
Cost of revenue	34,023	24,994	94,718	68,483
Research and development	23,965	17,706	67,955	54,027
Selling, general and administrative	80,220	66,556	240,254	187,233
Costs and Expenses, Total	138,208	109,256	402,927	309,743
Income from operations	62,355	44,766	159,424	109,570
Other income:
Investment income, net	2,175	969	5,397	2,385
Other (expense) income, net	(20)	(81)	10	(25)
Nonoperating Income (Expense), Total	2,155	888	5,407	2,360
Income before income taxes	64,510	45,654	164,831	111,930
Income tax provision (benefit)	19,648	32,208	(20,225)	36,607
Net income	$ 44,862	$ 13,446	$ 185,056	$ 75,323
Basic net income per share	$ 1.00	$ 0.30	$ 4.13	$ 1.71
Basic weighted average shares outstanding	45,046	44,247	44,852	44,095
Diluted net income per share	$ 0.97	$ 0.29	$ 4.01	$ 1.65
Diluted weighted average shares outstanding	46,136	45,869	46,147	45,731