Consolidated Statements of Income - Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 29, 2024	Feb. 28, 2023	Feb. 29, 2024	Feb. 28, 2023
Income Statement [Abstract]
Revenues	$ 545,945	$ 515,085	$ 1,088,161	$ 1,019,900
Operating expenses
Cost of services	255,142	240,806	506,763	467,848
Selling, general and administrative	108,807	104,582	209,518	210,178
Asset impairments	54	447	898	729
Total operating expenses	364,003	345,835	717,179	678,755
Operating income	181,942	169,250	370,982	341,145
Other income (expense), net
Interest income	2,847	2,903	5,859	5,108
Interest expense	(16,599)	(16,737)	(33,337)	(33,274)
Other income (expense), net	455	1,346	337	1,668
Total other income (expense), net	(13,297)	(12,488)	(27,141)	(26,498)
Income before income taxes	168,645	156,762	343,841	314,647
Provision for income taxes	27,705	25,169	54,346	46,256
Net income	$ 140,940	$ 131,593	$ 289,495	$ 268,391
Basic earnings per common share (in USD per share)	$ 3.70	$ 3.44	$ 7.61	$ 7.03
Diluted earnings per common share (in USD per share)	$ 3.65	$ 3.38	$ 7.49	$ 6.89
Basic weighted average common shares (in shares)	38,103	38,281	38,059	38,201
Diluted weighted average common shares (in shares)	38,650	38,981	38,646	38,947