Consolidated Statements of Income - Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Income Statement [Abstract]
Revenues	$ 431,119	$ 391,788	$ 855,844	$ 779,993
Operating expenses
Cost of services	199,395	195,523	406,544	383,611
Selling, general and administrative	108,376	80,132	203,291	159,219
Total operating expenses	307,771	275,655	609,835	542,830
Operating income	123,348	116,133	246,009	237,163
Other income (expense), net
Interest expense, net	(1,673)	(1,814)	(3,167)	(2,843)
Other income (expense), net	281	347	(956)	578
Income before income taxes	121,956	114,666	241,886	234,898
Provision for income taxes	12,018	18,023	24,301	37,049
Net income	$ 109,938	$ 96,643	$ 217,585	$ 197,849
Basic earnings per common share (in USD per share)	$ 2.91	$ 2.55	$ 5.77	$ 5.21
Diluted earnings per common share (in USD per share)	$ 2.84	$ 2.50	$ 5.63	$ 5.12
Basic weighted average common shares (in shares)	37,837	37,916	37,685	37,961
Diluted weighted average common shares (in shares)	38,761	38,620	38,628	38,658