Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue	$ 221,584	$ 200,563	$ 634,225	$ 562,351
Costs and expenses:
Cost of revenue	39,996	34,023	111,937	94,718
Research and development	25,655	23,965	73,413	67,955
Selling, general and administrative	85,674	80,220	257,708	240,254
Costs and Expenses, Total	151,325	138,208	443,058	402,927
Income from operations	70,259	62,355	191,167	159,424
Other income (expenses):
Investment income, net	3,086	2,175	9,066	5,397
Other income (expense), net	23,671	(20)	17,279	10
Nonoperating Income (Expense), Total	26,757	2,155	26,345	5,407
Income before income taxes	97,016	64,510	217,512	164,831
Income tax provision (benefit)	27,799	19,648	46,301	(20,225)
Net income	$ 69,217	$ 44,862	$ 171,211	$ 185,056
Basic net income per share	$ 1.53	$ 1.00	$ 3.79	$ 4.13
Basic weighted average shares outstanding	45,140	45,046	45,225	44,852
Diluted net income per share	$ 1.51	$ 0.97	$ 3.73	$ 4.01
Diluted weighted average shares outstanding	45,695	46,136	45,935	46,147