CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018
Current assets:
Cash and cash equivalents	$ 61,288	$ 42,975
Short-term marketable securities	299,228	319,274
Accounts receivable, net	67,511	70,010
Inventories	55,781	50,204
Prepaid expenses and other current assets	13,489	11,808
Total current assets	497,297	494,271
Long-term marketable securities	6,887	37,502
Property and equipment, net	127,324	117,167
Goodwill	33,948	35,808
In-process research and development	15,837	16,705
Long-term deferred tax assets, net	115,049	70,746
Other assets	15,697	14,176
Total assets	812,039	786,375
Current liabilities:
Accounts payable	25,673	23,565
Accrued expenses	38,930	46,147
Deferred revenue	12,075	14,970
Total current liabilities	76,678	84,682
Other long-term liabilities	815	776
Contingent consideration	10,331	10,490
Long-term deferred tax liabilities	856	903
Total liabilities	88,680	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 - 45,995,445 shares at December 31 , 2017 and 45,249,281 shares at March 31, 2017 Outstanding - 44,271,905 shares at December 31, 2017 and 43,673,286 shares at March 31, 2017	449	444
Additional paid in capital	637,974	619,905
Retained earnings	230,523	140,457
Treasury stock at cost - 1,891,713 shares at June 30, 2018 and 1,725,312 shares at March 31, 2018	(134,674)	(67,078)
Accumulated other comprehensive loss	(10,913)	(4,204)
Total stockholders' equity	723,359	689,524
Total liabilities and stockholders' equity	$ 812,039	$ 786,375