Unaudited Condensed Consolidated Statements of Shareholders' Investment - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022		Sep. 30, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 1,986,574,480	$ 1,916,318,989	$ 1,937,988,467	[1]	$ 1,963,943,128
Issuance of common stock from stock plan transactions	3,369,936	7,116,990	12,365,103		20,773,874
Issuance of common stock for equity investment purchases			$ 5,000,012
Repurchases of common stock (in shares)			(3,300,000)
Repurchases of common stock	(22,256,782)	(90,581,913)	$ (93,508,804)		(304,195,755)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	7,611,546	7,492,763	22,973,113		20,114,921
Dividends declared	(28,151,347)	(28,382,653)	(84,719,963)		(86,043,266)
Net income	72,655,995	76,660,548	232,589,023		276,617,836
Other comprehensive (loss) income	14,241,836	(994,438)	1,358,713		(3,580,452)
Balance at end of period	$ 2,034,045,664	$ 1,887,630,286	$ 2,034,045,664		$ 1,887,630,286
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	235,132,265	238,966,589	236,440,840		243,692,869
Balance at beginning of period	$ 14,107,936	$ 14,337,995	$ 14,186,450		$ 14,621,572
Issuance of common stock from stock plan transactions (in shares)	315,433	398,873	1,284,615		1,838,789
Issuance of common stock from stock plan transactions	$ 18,926	$ 23,932	$ 77,077		$ 110,327
Issuance of common stock for equity investment purchases (in shares)			162,433
Issuance of common stock for equity investment purchases			$ 9,746
Repurchases of common stock (in shares)	(850,306)	(2,830,850)	(3,290,496)		(8,997,046)
Repurchases of common stock	$ (51,019)	$ (169,851)	$ (197,430)		$ (539,823)
Ending balance (in shares)	234,597,392	236,534,612	234,597,392		236,534,612
Balance at end of period	$ 14,075,843	$ 14,192,076	$ 14,075,843		$ 14,192,076
Additional  Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	900,576,404	859,678,392	879,413,385		852,771,508
Issuance of common stock from stock plan transactions	3,351,010	7,093,058	12,288,026		20,663,547
Issuance of common stock for equity investment purchases			4,990,266
Repurchases of common stock	(2,916,551)	(9,200,264)	(11,042,381)		(28,486,027)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	7,611,546	7,492,763	22,973,113		20,114,921
Balance at end of period	908,622,409	865,063,949	908,622,409		865,063,949
Retained  Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	1,082,846,019	1,038,037,564	1,042,461,388		1,089,698,996
Repurchases of common stock	(19,289,212)	(81,211,798)	(82,268,993)		(275,169,905)
Dividends declared	(28,151,347)	(28,382,653)	(84,719,963)		(86,043,266)
Net income	72,655,995	76,660,548	232,589,023		276,617,836
Balance at end of period	1,108,061,455	1,005,103,661	1,108,061,455		1,005,103,661
Accumulated  Other Comprehensive (Loss) Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(10,955,879)	4,265,038	1,927,244		6,851,052
Other comprehensive (loss) income	14,241,836	(994,438)	1,358,713		(3,580,452)
Balance at end of period	$ 3,285,957	$ 3,270,600	$ 3,285,957		$ 3,270,600

[1] The condensed consolidated balance sheet at December 31, 2021 has been derived from the audited consolidated financial statements at that date, but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.