Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 209,764	$ 204,974	$ 374,614	$ 412,640
Costs and expenses:
Cost of revenue	38,736	34,867	74,719	71,940
Research and development	30,525	23,969	56,882	47,759
Selling, general and administrative	79,167	85,956	147,611	172,034
Costs and Expenses, Total	148,428	144,792	279,212	291,733
Income from operations	61,336	60,182	95,402	120,907
Other income (expense):
Investment income, net	1,822	2,932	4,219	5,981
Other income (expense), net	9,757	(45,756)	34,370	(6,392)
Nonoperating Income (Expense), Total	11,579	(42,824)	38,589	(411)
Income before income taxes	72,915	17,358	133,991	120,496
Income tax provision	10,702	4,287	27,190	18,502
Net income	$ 62,213	$ 13,071	$ 106,801	$ 101,994
Basic net income per share	$ 1.38	$ 0.29	$ 2.37	$ 2.25
Basic weighted average shares outstanding	45,104	45,319	45,057	45,267
Diluted net income per share	$ 1.36	$ 0.28	$ 2.34	$ 2.22
Diluted weighted average shares outstanding	45,661	45,912	45,609	46,031