Unaudited Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 97,578,261	$ 87,528,626
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	24,041,648	24,711,500
(Gain) on disposal of assets	(106,743)	(33,982)
Loss on disposal of assets	41,843	11,067
(Gain) on sale of investments and equity method investment income	(1,199,707)	(367,879)
Loss on sale of investments and equity method investment losses	1,671,583	704,214
Change in deferred income taxes	141,959	0
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	8,519,535	6,788,337
Change in operating assets and liabilities:
Accounts receivable, net	(56,373,376)	(31,666,772)
Inventories	2,590,294	(46,469,079)
Prepaid expenses and other	(629,502)	16,082,077
Accounts payable	11,112,425	42,968,193
Accrued liabilities, excluding dividends declared	33,525,890	15,702,241
Net cash provided by operating activities	120,914,110	115,958,543
Activity in available-for-sale securities:
Sales proceeds	3,128,110	37,158,611
Maturities and calls	1,465,000	1,000,000
Purchases	(32,178,155)	(15,889,063)
Plant and equipment additions	(42,819,075)	(23,892,169)
Proceeds from sale of plant and equipment	118,410	33,740
Increase in other assets	(2,110,935)	(455,419)
Net cash used for investing activities	(72,396,645)	(2,044,300)
CASH FLOWS USED FOR FINANCING ACTIVITIES:
Issuance of common stock from stock plan transactions	5,956,022	3,324,147
Cash dividends paid	(28,099,993)	(28,589,625)
Repurchases of common stock	(25,675,972)	(71,252,022)
Net cash used for financing activities	(47,819,943)	(96,517,500)
NET INCREASE IN CASH AND CASH EQUIVALENTS	697,522	17,396,743
CASH, CASH EQUIVALENTS, and RESTRICTED CASH, beginning of period	218,754,638	262,311,670
CASH, CASH EQUIVALENTS, and RESTRICTED CASH, end of period	$ 219,452,160	$ 279,708,413