Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Mar. 31, 2020
Current assets:
Cash and cash equivalents	$ 202,241	$ 192,341
Short-term marketable securities	330,843	250,775
Accounts receivable, net	80,909	84,650
Inventories	83,209	90,088
Prepaid expenses and other current assets	19,419	18,009
Total current assets	716,621	635,863
Long-term marketable securities	202,613	207,795
Property and equipment, net	175,582	164,931
Goodwill	78,122	31,969
In-process research and development	42,895	14,913
Deferred tax assets	29,547	43,336
Other assets	82,594	117,655
Total assets	1,327,974	1,216,462
Current liabilities:
Accounts payable	21,734	32,774
Accrued expenses	57,227	75,107
Deferred revenue	21,314	19,147
Other current liabilities	4,938	4,857
Total current liabilities	105,213	131,885
Contingent consideration	24,417	9,000
Deferred tax liabilities	4,251	806
Other long-term liabilities	11,684	9,305
Total liabilities	145,565	150,996
Commitments and contingencies (Note 14)
Stockholders' equity:
Class B Preferred Stock, $.01 par value Authorized - 1,000,000 shares; Issued and outstanding - none
Common stock, $.01 par value Authorized - 100,000,000 shares; Issued - 47,435,945 shares at June 30, 2019 and 47,026,226 shares at March 31, 2019 Outstanding - 45,374,278 shares at June 30, 2019 and 45,122,985 shares at March 31, 2019	452	451
Additional paid in capital	767,527	739,133
Retained earnings	709,283	602,482
Treasury stock at cost - 2,657,140 shares at September 30, 2020 and 2,533,374 shares at March 31, 2020	(287,654)	(265,411)
Accumulated other comprehensive loss	(7,199)	(11,189)
Total stockholders' equity	1,182,409	1,065,466
Total liabilities and stockholders' equity	$ 1,327,974	$ 1,216,462