Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Aug. 31, 2021	Aug. 31, 2020
Deferred tax assets:
Operating lease liabilities	$ 20,645	$ 22,676
Amortizable goodwill and other intangibles	13,490	17,455
Employee benefit accruals	14,007	9,246
Net operating loss carryforwards	7,642	8,484
Environmental liabilities	10,508	7,938
Other contingencies	5,044	4,133
State credit carryforwards	7,216	7,933
Federal credit carryforwards		5,116
Inventory valuation methods	2,129	2,865
Other	2,459	2,941
Valuation allowances	(14,522)	(16,933)
Total deferred tax assets	68,618	71,854
Deferred tax liabilities:
Accelerated depreciation and other basis differences	43,304	39,596
Operating lease right-of-use assets	19,895	21,104
Investment in operating partnerships	12,410	14,703
Uncertain tax positions		4,936
Prepaid expense acceleration and other	6,041	2,655
Total deferred tax liabilities	81,650	82,994
Net deferred tax liabilities	$ (13,032)	$ (11,140)