CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents	$ 110,091	$ 97,513
Short-term investments	269,498	297,981
Accounts receivable	20,866	24,729
Inventories	14,709	12,748
Deferred income taxes	12,548	12,326
Other current assets	4,683	2,387
Total current assets	432,395	447,684
PROPERTY AND EQUIPMENT, net of accumulated depreciation of $28,799 and $27,897	22,362	22,407
ACQUIRED TECHNOLOGY, net of accumulated amortization of $57,587 and $54,837	69,265	72,015
INVESTMENTS	16,092	2,187
DEFERRED INCOME TAXES	15,287	14,945
OTHER ASSETS	645	174
TOTAL ASSETS	556,046	559,412
CURRENT LIABILITIES:
Accounts payable	7,294	6,849
Accrued expenses	6,746	17,387
Deferred revenue	10,353	10,107
Other current liabilities	757	167
Total current liabilities	25,150	34,510
DEFERRED REVENUE	35,515	35,543
RETIREMENT PLAN BENEFIT LIABILITY	24,485	22,594
Total liabilities	$ 85,150	$ 92,647
COMMITMENTS AND CONTINGENCIES (Note 13)
SHAREHOLDERS' EQUITY:
Preferred Stock, par value $0.01 per share, 5,000,000 shares authorized, 200,000 shares of Series A Nonconvertible Preferred Stock issued and outstanding (liquidation value of $7.50 per share or $1,500)	$ 2	$ 2
Common Stock, par value $0.01 per share, 100,000,000 shares authorized, 48,147,715 and 48,132,223 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	483	482
Additional paid-in capital	592,769	589,885
Accumulated deficit	(71,678)	(73,627)
Accumulated other comprehensive loss	(10,522)	(9,819)
Treasury stock, at cost (1,357,863 shares at March 31, 2016 and December 31, 2015)	(40,158)	(40,158)
Total shareholders’ equity	470,896	466,765
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 556,046	$ 559,412