CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018
Current assets:
Cash and cash equivalents	$ 84,181	$ 42,975
Short-term marketable securities	373,975	319,274
Accounts receivable, net	88,215	70,010
Inventories	71,808	50,204
Prepaid expenses and other current assets	10,549	11,808
Total current assets	628,728	494,271
Long-term marketable securities		37,502
Property and equipment, net	138,455	117,167
Goodwill	33,260	35,808
In-process research and development	15,516	16,705
Long-term deferred tax assets, net	96,450	70,746
Other assets	44,707	14,176
Total assets	957,116	786,375
Current liabilities:
Accounts payable	26,179	23,565
Accrued expenses	51,721	46,147
Deferred revenue	15,080	14,970
Total current liabilities	92,980	84,682
Other long-term liabilities	1,185	776
Contingent consideration	10,583	10,490
Long-term deferred tax liabilities	838	903
Total liabilities	105,586	96,851
Commitments and contingencies (Note 11)
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 - 46,959,653 shares at December 31, 2018 and 46,100,649 shares at March 31, 2018 Outstanding - 45,058,049 shares at December 31, 2018 and 44,375,337 shares at March 31, 2018	451	444
Additional paid in capital	676,171	619,905
Retained earnings	325,513	140,457
Treasury stock at cost - 1,901,604 shares at December 31, 2018 and 1,725,312 shares at March 31, 2018	(138,289)	(67,078)
Accumulated other comprehensive loss	(12,316)	(4,204)
Total stockholders' equity	851,530	689,524
Total liabilities and stockholders' equity	$ 957,116	$ 786,375