Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Current assets:
Cash and cash equivalents	$ 150,279	$ 121,021
Short-term marketable securities	295,041	370,677
Accounts receivable, net	94,319	90,809
Inventories	90,295	80,942
Prepaid expenses and other current assets	17,498	13,748
Total current assets	647,432	677,197
Long-term marketable securities	106,025	21,718
Property and equipment, net	157,896	145,005
Goodwill	31,727	32,601
In-process research and development	14,800	15,208
Long-term deferred tax assets, net	67,277	77,502
Other assets	99,191	85,115
Total assets	1,124,348	1,054,346
Current liabilities:
Accounts payable	31,736	32,185
Accrued expenses	57,907	57,420
Deferred revenue	19,322	16,393
Other current liabilities	3,264
Total current liabilities	112,229	105,998
Contingent consideration	10,236	9,575
Long-term deferred tax liabilities	800	822
Other long-term liabilities	9,626	1,061
Total liabilities	132,891	117,456
Commitments and contingencies (Note 13)
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 - 47,484,911 shares at September 30, 2019 and 47,026,226 shares at March 31, 2019 Outstanding - 45,238,952 shares at September 30, 2019 and 45,122,985 shares at March 31, 2019	452	451
Additional paid in capital	722,020	690,507
Retained earnings	501,467	399,473
Treasury stock at cost - 2,245,959 shares at September 30, 2019 and 1,903,241 shares at March 31, 2019	(214,926)	(138,852)
Accumulated other comprehensive loss	(17,556)	(14,689)
Total stockholders' equity	991,457	936,890
Total liabilities and stockholders' equity	$ 1,124,348	$ 1,054,346