CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 141,033	$ 144,927
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	20,128	17,982
Amortization of intangibles	11,442	14,562
Amortization of premium and discount on investments, net	(9,436)	(3,469)
Stock-based compensation to employees	17,359	22,528
Stock-based compensation to Board of Directors and Scientific Advisory Board	1,264	1,121
Deferred income tax expense (benefit)	7,556	(7,876)
Retirement plan expense, net of benefit payments	2,347	3,998
Decrease (increase) in assets:
Accounts receivable	(29,528)	29,446
Inventory	1,814	(46,034)
Other current assets	(37,653)	(9,057)
Other assets	8,292	2,282
Increase (decrease) in liabilities:
Accounts payable and accrued expenses	(32)	7,217
Other current liabilities	(24,186)	(543)
Deferred revenue	11,809	(63,066)
Other liabilities	(4,502)	10,156
Net cash provided by operating activities	117,707	124,174
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(52,208)	(31,119)
Purchases of intangibles	(66,563)	(4,761)
Purchases of investments	(303,004)	(464,766)
Proceeds from sale and maturity of investments	346,407	302,872
Net cash used in investing activities	(75,368)	(197,774)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	1,532	1,247
Payment of withholding taxes related to stock-based compensation to employees	(7,895)	(9,150)
Cash dividends paid	(50,083)	(42,740)
Net cash used in financing activities	(56,446)	(50,643)
DECREASE IN CASH AND CASH EQUIVALENTS	(14,107)	(124,243)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	93,430	311,993
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 79,323	$ 187,750