CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 103,777	$ 132,840
Short-term investments	353,651	287,446
Accounts receivable	35,583	52,355
Inventory	56,043	36,265
Other current assets	20,311	10,276
Total current assets	569,365	519,182
PROPERTY AND EQUIPMENT, net of accumulated depreciation of $40,769 and $36,368	62,348	56,450
ACQUIRED TECHNOLOGY, net of accumulated amortization of $101,611 and $91,312	121,230	131,529
OTHER INTANGIBLE ASSETS, net of accumulated amortization of $2,687 and $2,000	14,153	14,840
GOODWILL	15,535	15,535
INVESTMENTS		14,794
DEFERRED INCOME TAXES	10,534	27,022
OTHER ASSETS	40,084	604
TOTAL ASSETS	833,249	779,956
CURRENT LIABILITIES:
Accounts payable	7,863	13,774
Accrued expenses	24,405	35,019
Deferred revenue	69,247	14,981
Other current liabilities	25	50
Total current liabilities	101,540	63,824
DEFERRED REVENUE	28,344	23,902
RETIREMENT PLAN BENEFIT LIABILITY	34,350	33,176
OTHER LIABILITIES	18,334
Total liabilities	182,568	120,902
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, 200,000,000 shares authorized, 48,650,696 and 48,476,034 shares issued, and 47,289,059 and 47,118,171 shares outstanding, at June 30, 2018 and December 31, 2017, respectively	487	485
Additional paid-in capital	608,932	611,063
Retained earnings	92,346	99,126
Accumulated other comprehensive loss	(10,451)	(11,464)
Treasury stock, at cost (1,361,637 and 1,357,863 shares at June 30, 2018 and December 31, 2017, respectively)	(40,635)	(40,158)
Total shareholders’ equity	650,681	659,054
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 833,249	$ 779,956