UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' INVESTMENT - USD ($)	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 2,472,099,655	$ 2,312,517,069
Issuance of common stock from stock plan transactions (in shares)	700,000
Issuance of common stock from stock plan transactions	$ 4,933,702	16,833,986
Repurchases of common stock (in shares)	(3,100,000)
Repurchases of common stock	$ (76,006,073)	(43,039,087)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	8,671,763	10,473,792
Dividends declared	(26,977,308)	(27,743,481)
Capital contributions, net	442,500
Net income	94,874,045	108,230,714
Other comprehensive income (loss)	1,379,219	(909,204)
Balance at end of period	2,479,417,503	2,376,363,789
Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	2,467,950,655	2,312,517,069
Issuance of common stock from stock plan transactions	4,933,702	16,833,986
Repurchases of common stock	(76,006,073)	(43,039,087)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	8,671,763	10,473,792
Dividends declared	(26,977,308)	(27,743,481)
Net income	94,874,045	108,230,714
Other comprehensive income (loss)	1,379,219	(909,204)
Balance at end of period	$ 2,474,826,003	$ 2,376,363,789
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period (in shares)	227,207,472	231,455,443
Balance at beginning of period	$ 13,632,448	$ 13,887,326
Issuance of common stock from stock plan transactions (in shares)	709,996	944,345
Issuance of common stock from stock plan transactions	$ 42,600	$ 56,661
Repurchases of common stock (in shares)	(3,100,351)	(1,200,903)
Repurchases of common stock	$ (186,021)	$ (72,054)
Balance at end of period (in shares)	224,817,117	231,198,885
Balance at end of period	$ 13,489,027	$ 13,871,933
Additional  Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	1,010,440,420	968,245,875
Issuance of common stock from stock plan transactions	4,891,102	16,777,325
Repurchases of common stock	(12,246,386)	(4,443,340)
Stock-based compensation expense related to stock options, employee stock purchases and restricted stock	8,671,763	10,473,792
Balance at end of period	1,011,756,899	991,053,652
Retained  Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	1,450,287,128	1,336,940,990
Repurchases of common stock	(63,573,666)	(38,523,693)
Dividends declared	(26,977,308)	(27,743,481)
Net income	94,874,045	108,230,714
Balance at end of period	1,454,610,199	1,378,904,530
Accumulated  Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(6,409,341)	(6,557,122)
Other comprehensive income (loss)	1,379,219	(909,204)
Balance at end of period	(5,030,122)	(7,466,326)
Equity Attributable to Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	4,149,000	0
Capital contributions, net	442,500
Balance at end of period	$ 4,591,500	$ 0