CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
CURRENT ASSETS:
Cash and cash equivalents	$ 357,424	$ 311,993
Short-term investments	325,055	351,194
Accounts receivable	104,947	107,639
Inventory	143,240	134,160
Other current assets	29,120	20,948
Total current assets	959,786	925,934
PROPERTY AND EQUIPMENT, net of accumulated depreciation of $97,979 and $92,461	131,879	128,832
ACQUIRED TECHNOLOGY, net of accumulated amortization of $178,782 and $173,635	44,521	49,668
OTHER INTANGIBLE ASSETS, net of accumulated amortization of $7,918 and $7,565	9,370	9,711
GOODWILL	15,535	15,535
INVESTMENTS	164,130	168,076
DEFERRED INCOME TAXES	35,788	33,453
OTHER ASSETS	126,222	135,710
TOTAL ASSETS	1,487,231	1,466,919
CURRENT LIABILITIES:
Accounts payable	27,064	14,955
Accrued expenses	26,960	45,474
Deferred revenue	111,778	120,864
Other current liabilities	12,452	6,645
Total current liabilities	178,254	187,938
DEFERRED REVENUE	31,735	36,217
RETIREMENT PLAN BENEFIT LIABILITY	67,481	66,773
OTHER LIABILITIES	78,461	76,077
Total liabilities	355,931	367,005
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, 49,099,830 and 49,065,924 shares issued, and 47,734,182 and 47,700,276 shares outstanding, at March 31, 2022 and December 31, 2021, respectively	491	491
Additional paid-in capital	658,050	658,728
Retained earnings	535,936	500,212
Accumulated other comprehensive loss	(21,895)	(18,235)
Treasury stock, at cost (1,365,648 shares at September 30, 2021 and December 31, 2020)	(41,284)	(41,284)
Total shareholders’ equity	1,131,300	1,099,914
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 1,487,231	$ 1,466,919