Unaudited Condensed Consolidated Statements of Shareholders' Investment - USD ($)	3 Months Ended
	Mar. 31, 2023		Mar. 31, 2022
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 2,065,792,821	[1]	$ 1,937,988,467
Issuance of common stock from stock plan transactions	$ 5,956,022		3,324,147
Repurchases of common stock (in shares)	(1,000,000)
Repurchases of common stock	$ (28,462,632)		(71,252,022)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	8,519,535		6,788,337
Dividends declared	(28,046,798)		(28,354,003)
Net income	97,578,261		87,528,626
Other comprehensive (loss) income	1,918,437		(7,054,652)
Balance at end of period	$ 2,123,255,646		$ 1,928,968,900
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	234,169,335		236,440,840
Balance at beginning of period	$ 14,050,160		$ 14,186,450
Issuance of common stock from stock plan transactions (in shares)	603,636		476,688
Issuance of common stock from stock plan transactions	$ 36,218		$ 28,601
Repurchases of common stock (in shares)	(1,046,926)		(2,440,190)
Repurchases of common stock	$ (62,815)		$ (146,411)
Ending balance (in shares)	233,726,045		234,477,338
Balance at end of period	$ 14,023,563		$ 14,068,640
Additional  Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	917,499,323		879,413,385
Issuance of common stock from stock plan transactions	5,919,804		3,295,546
Repurchases of common stock	(3,653,772)		(8,125,830)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	8,519,535		6,788,337
Balance at end of period	928,284,890		881,371,438
Retained  Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	1,148,386,272		1,042,461,388
Repurchases of common stock	(24,746,045)		(62,979,781)
Dividends declared	(28,046,798)		(28,354,003)
Net income	97,578,261		87,528,626
Balance at end of period	1,193,171,690		1,038,656,230
Accumulated  Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(14,142,934)		1,927,244
Other comprehensive (loss) income	1,918,437		(7,054,652)
Balance at end of period	$ (12,224,497)		$ (5,127,408)

[1] The condensed consolidated balance sheet at December 31, 2022 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.