CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 726,279	$ 630,012
Short-term investments	720	99,996
Accounts receivable	91,327	82,261
Inventory	101,422	91,591
Other current assets	39,587	20,746
Total current assets	959,335	924,606
PROPERTY AND EQUIPMENT, net of accumulated depreciation of $76,756 and $72,493	107,815	102,113
ACQUIRED TECHNOLOGY, net of accumulated amortization of $158,197 and $153,050	65,106	70,253
OTHER INTANGIBLE ASSETS, net of accumulated amortization of $6,496 and $6,155	10,641	10,685
GOODWILL	15,535	15,535
INVESTMENTS	8,500	5,000
DEFERRED INCOME TAXES	36,864	37,695
OTHER ASSETS	106,704	103,341
TOTAL ASSETS	1,310,500	1,269,228
CURRENT LIABILITIES:
Accounts payable	14,741	13,801
Accrued expenses	19,171	41,404
Deferred revenue	128,546	105,215
Other current liabilities	3,874	4,540
Total current liabilities	166,332	164,960
DEFERRED REVENUE	49,578	57,086
RETIREMENT PLAN BENEFIT LIABILITY	79,246	78,527
OTHER LIABILITIES	62,876	55,941
Total liabilities	358,032	356,514
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, 49,050,776 and 49,013,476 shares issued, and 47,685,128 and 47,647,828 shares outstanding, at March 31, 2021 and December 31, 2020, respectively	491	490
Additional paid-in capital	632,138	635,595
Retained earnings	396,130	353,930
Accumulated other comprehensive loss	(35,009)	(36,019)
Treasury stock, at cost (1,365,648 shares at March 31, 2021 and December 31, 2020)	(41,284)	(41,284)
Total shareholders’ equity	952,468	912,714
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 1,310,500	$ 1,269,228