Unaudited Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 87,528,626	$ 113,450,870
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	24,711,500	25,599,131
(Gain) on disposal of assets	(33,982)	(2,391)
Loss on disposal of assets	11,067	131,490
(Gain) on sale of investments	(367,879)	(486,433)
Loss on sale of investments	704,214	41,681
Change in deferred income taxes	0	(1,544,501)
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	6,788,337	5,894,645
Change in operating assets and liabilities:
Accounts receivable, net	(31,666,772)	7,253,692
Inventories	(46,469,079)	(6,768,464)
Prepaid expenses and other	16,082,077	768,229
Accounts payable	42,968,193	22,277,513
Accrued liabilities, excluding dividends declared and short-term debt	15,702,241	24,233,539
Net cash provided by operating activities	115,958,543	190,849,001
Activity in available-for-sale securities:
Sales proceeds	37,158,611	15,019,323
Maturities and calls	1,000,000	2,000,000
Purchases	(15,889,063)	(31,379,609)
Plant and equipment additions	(23,892,169)	(12,599,388)
Proceeds from sale of plant and equipment	33,740	17,744
Acquisition of businesses, net of cash acquired	0	(12,023,440)
Increase in other assets	(455,419)	(1,643,884)
Net cash used for investing activities	(2,044,300)	(40,609,254)
CASH FLOWS (USED FOR) FINANCING ACTIVITIES:
Issuance of common stock from stock plan transactions	3,324,147	9,265,840
Cash dividends paid	(28,589,625)	(29,243,108)
Repurchases of common stock	(71,252,022)	(97,692,763)
Net cash (used for) financing activities	(96,517,500)	(117,670,032)
NET INCREASE IN CASH AND CASH EQUIVALENTS	17,396,743	32,569,715
CASH AND CASH EQUIVALENTS, beginning of period	262,311,670	423,371,036
CASH AND CASH EQUIVALENTS, end of period	$ 279,708,413	$ 455,940,751