Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenue	$ 231,663	$ 221,584	$ 606,277	$ 634,225
Costs and expenses:
Cost of revenue	41,110	39,996	115,829	111,937
Research and development	33,004	25,655	89,886	73,413
Selling, general and administrative	86,198	85,674	233,809	257,708
Costs and Expenses, Total	160,312	151,325	439,524	443,058
Income from operations	71,351	70,259	166,753	191,167
Other income:
Investment income, net	1,449	3,086	5,668	9,066
Other income, net	7,935	23,671	42,305	17,279
Nonoperating Income (Expense), Total	9,384	26,757	47,973	26,345
Income before income taxes	80,735	97,016	214,726	217,512
Income tax provision	18,867	27,799	46,057	46,301
Net income	$ 61,868	$ 69,217	$ 168,669	$ 171,211
Basic net income per share	$ 1.37	$ 1.53	$ 3.74	$ 3.79
Basic weighted average shares outstanding	45,201	45,140	45,105	45,225
Diluted net income per share	$ 1.35	$ 1.51	$ 3.69	$ 3.73
Diluted weighted average shares outstanding	45,706	45,695	45,653	45,935