Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Current assets:
Cash and cash equivalents	$ 121,021	$ 42,975
Short-term marketable securities	370,677	319,274
Accounts receivable, net	90,809	70,010
Inventories	80,942	50,204
Prepaid expenses and other current assets	13,748	11,808
Total current assets	677,197	494,271
Long-term marketable securities	21,718	37,502
Property and equipment, net	145,005	117,167
Goodwill	32,601	35,808
In-process research and development	15,208	16,705
Long-term deferred tax assets, net	77,502	70,746
Other assets	85,115	14,176
Total assets	1,054,346	786,375
Current liabilities:
Accounts payable	32,185	23,565
Accrued expenses and other liabilities	57,420	46,147
Deferred revenue	16,393	14,970
Total current liabilities	105,998	84,682
Other long-term liabilities	1,061	776
Contingent consideration	9,575	10,490
Long-term deferred tax liabilities	822	903
Total liabilities	117,456	96,851
Commitments and contingencies (Note 12)
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 - 47,026,226 shares at March 31, 2019 and 46,100,649 shares at March 31, 2018; Outstanding - 45,122,985 shares at March 31, 2019 and 44,375,337 shares at March 31, 2018	451	444
Additional paid in capital	690,507	619,905
Retained earnings	399,473	140,457
Treasury stock at cost - 1,903,241 shares at March 31, 2019 and 1,725,312 shares at March 31, 2018	(138,852)	(67,078)
Accumulated other comprehensive loss	(14,689)	(4,204)
Total stockholders' equity	936,890	689,524
Total liabilities and stockholders' equity	$ 1,054,346	$ 786,375