Notes Payable and Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Aug. 31, 2021	Feb. 19, 2021	Aug. 31, 2020
Debt Instrument [Line Items]
Notes payable	$ 1,740,859		$ 1,575,491
Total long-term debt	1,578,422
Debt Issuance Costs, Net	(4,090)		(4,771)
Long-term Debt, Fair Value	1,618,361
Less current portion	38,450		189,287
Long-term portion	1,579,911		1,601,836
Long-term debt
Debt Instrument [Line Items]
Finance Lease, Liability	28,590		23,467
Total Long-term Debt
Debt Instrument [Line Items]
Finance Lease, Liability	$ 36,034		31,460
Unsecured debt | Minimum
Debt Instrument [Line Items]
Interest rate	2.60%
Unsecured debt | Maximum
Debt Instrument [Line Items]
Interest rate	9.00%
Notes Payable, Other Payables [Member] | Notes Payable, Other Payables [Member] | Revolving credit facility
Debt Instrument [Line Items]
Notes payable	$ 864,147		763,215
Private placement, payable in equal installments beginning in 2017 through 2021 | Unsecured debt
Debt Instrument [Line Items]
Total long-term debt	0		20,000
Private placement, payable in equal installments beginning in 2017 through 2021 | Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 100,000
Interest rate	4.00%
Private placement, payable in its entirety in 2021 | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 160,000
Total long-term debt	$ 0		162,090
Interest rate	4.52%
Private placement, payable in its entirety in 2023 | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 130,000
Total long-term debt	$ 134,873		137,623
Interest rate	4.67%
Private placement, payable in 2023 152k [Member] [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 152,000
Total long-term debt	$ 152,000		152,000
Interest rate	4.39%
Private placement, payable in 2025 80k [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 80,000
Total long-term debt	$ 80,000		80,000
Interest rate	3.85%
Private placement, payable in 2025 100k [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 100,000
Total long-term debt	$ 100,000		100,000
Interest rate	3.80%
Private placement, payable in 2025 150k [Member] [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 150,000
Total long-term debt	$ 153,101		154,012
Interest rate	4.58%
Private placement, payable in its entirety in 2026 | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 80,000
Total long-term debt	$ 80,000		80,000
Interest rate	4.82%
Private placement, payable in its entirety in 2027 [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 58,000
Total long-term debt	$ 58,000		58,000
Interest rate	4.69%
Private placement, payable in its entirety in 2028 [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 95,000
Total long-term debt	$ 95,000		95,000
Interest rate	4.74%
Private placement, payable in its entirety in 2031 [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 100,000
Total long-term debt	$ 100,000		100,000
Interest rate	4.89%
Private placement, payable in its entirety 2033 [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 100,000
Total long-term debt	$ 100,000		100,000
Interest rate	4.71%
Private placement, payable in its entirety in 2036 [Member] | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 125,000
Total long-term debt	$ 125,000		125,000
Interest rate	5.40%
Private Placement [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 1,552,974		1,363,725
Term loans, 430K payable in 2025 [Member] | Unsecured debt
Debt Instrument [Line Items]
Total long-term debt	0	$ 366,000	366,000
Bank financing [Member]
Debt Instrument [Line Items]
Total long-term debt	0		366,000
Other notes and contracts | Secured debt
Debt Instrument [Line Items]
Total long-term debt	$ 33,443		34,709
us-gaap_DebtInstrumentName | us-gaap_LongtermDebtType
Debt Instrument [Line Items]
Long-term Debt, Fair Value			1,791,123
Less current portion			$ 189,287
Unsecured term loans | Unsecured debt
Debt Instrument [Line Items]
Interest rate	2.25%
Additional Private placement, payable in its entirety in 2027 | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 95,000
Total long-term debt	$ 95,000
Interest rate	3.24%
Private placement, payable in its entirety in 2030 | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 100,000
Total long-term debt	$ 100,000
Interest rate	3.48%
Private placement, payable in its entirety in 2032 | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 65,000
Total long-term debt	$ 65,000
Interest rate	3.58%
Private placement, payable in its entirety in 2035 | Unsecured debt
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 115,000
Total long-term debt	$ 115,000
Interest rate	3.73%