CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 222,744	$ 131,627
Short-term investments	417,032	514,461
Accounts receivable	82,592	60,452
Inventory	74,068	63,953
Other current assets	15,635	21,946
Total current assets	812,071	792,439
PROPERTY AND EQUIPMENT, net of accumulated depreciation of $60,891 and $57,276	88,350	87,872
ACQUIRED TECHNOLOGY, net of accumulated amortization of $137,613 and $132,468	85,629	90,774
OTHER INTANGIBLE ASSETS, net of accumulated amortization of $5,113 and $4,768	11,727	12,072
GOODWILL	15,535	15,535
INVESTMENTS	5,000	5,000
DEFERRED INCOME TAXES	28,729	30,375
OTHER ASSETS	89,335	86,090
TOTAL ASSETS	1,136,376	1,120,157
CURRENT LIABILITIES:
Accounts payable	10,370	13,296
Accrued expenses	21,648	49,022
Deferred revenue	99,565	97,333
Other current liabilities	4,971	1,857
Total current liabilities	136,554	161,508
DEFERRED REVENUE	49,866	47,529
RETIREMENT PLAN BENEFIT LIABILITY	51,711	51,117
OTHER LIABILITIES	51,548	48,554
Total liabilities	289,679	308,708
COMMITMENTS AND CONTINGENCIES (Note 15)
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, 48,910,232 and 48,852,193 shares issued, and 47,544,584 and 47,486,545 shares outstanding, at March 31, 2020 and December 31, 2019, respectively	489	489
Additional paid-in capital	621,967	620,236
Retained earnings	280,060	249,003
Accumulated other comprehensive loss	(14,537)	(16,997)
Treasury stock, at cost (1,365,648 shares at March 31, 2020 and December 31, 2019)	(41,284)	(41,284)
Total shareholders’ equity	846,697	811,449
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 1,136,376	$ 1,120,157