Consolidated Statements of Shareholders' Investment - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	243,692,869
Beginning balance	$ 1,963,943,128	$ 1,938,087,820	$ 1,861,751,660
Issuance of common stock from stock plan transactions	29,808,787	41,803,640	77,821,151
Issuance of common stock related to acquisitions		3,559,229
Repurchases of common stock	(324,643,135)	(288,480,506)	(331,471,392)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	27,421,645	30,797,327	21,671,192
Dividends declared	(114,415,382)	(117,528,158)	(116,679,965)
Net income	360,797,232	347,563,621	424,683,939
Other comprehensive income (loss)	$ (4,923,808)	$ 8,140,155	311,235
Ending balance (in shares)	236,440,840	243,692,869
Ending balance	$ 1,937,988,467	$ 1,963,943,128	$ 1,938,087,820
Common Stocks
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	243,692,869	251,277,515	259,328,613
Beginning balance	$ 14,621,572	$ 15,076,651	$ 15,559,717
Issuance of common stock from stock plan transactions (in shares)	2,343,169	2,897,689	5,724,840
Issuance of common stock from stock plan transactions	$ 140,590	$ 173,861	$ 343,490
Issuance of common stock related to acquisitions (in shares)		163,718
Issuance of common stock related to acquisitions		$ 9,823
Repurchases of common stock (in shares)	(9,595,198)	(10,646,053)	(13,775,938)
Repurchases of common stock	$ (575,712)	$ (638,763)	$ (826,556)
Ending balance (in shares)	236,440,840	243,692,869	251,277,515
Ending balance	$ 14,186,450	$ 14,621,572	$ 15,076,651
Additional  Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	852,771,508	807,928,139	745,324,144
Issuance of common stock from stock plan transactions	29,668,197	41,629,779	77,477,661
Issuance of common stock related to acquisitions		3,549,406
Repurchases of common stock	(30,447,965)	(31,133,143)	(36,544,858)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	27,421,645	30,797,327	21,671,192
Ending balance	879,413,385	852,771,508	807,928,139
Retained  Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,089,698,996	1,116,372,133	1,102,468,137
Repurchases of common stock	(293,619,458)	(256,708,600)	(294,099,978)
Dividends declared	(114,415,382)	(117,528,158)	(116,679,965)
Net income	360,797,232	347,563,621	424,683,939
Ending balance	1,042,461,388	1,089,698,996	1,116,372,133
Accumulated  Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	6,851,052	(1,289,103)	(1,600,338)
Other comprehensive income (loss)	(4,923,808)	8,140,155	311,235
Ending balance	$ 1,927,244	$ 6,851,052	$ (1,289,103)