Benefit Plans - Schedule of Pension Plans' Fair Value Measurements (Details) - Pension Benefits - USD ($) $ in Thousands	Aug. 31, 2019	Aug. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	$ 909,427	$ 829,616
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	7,938	7,424
Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value		692
Equity Securities: Common/collective trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	209,860	216,962
Fixed Income Securities: Common/collective trust [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	574,296	500,637
Partnership and joint venture interests
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	101,641	101,954
Other assets
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	15,692	1,947
Level 1
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	7,938	8,116
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	7,938	7,424
Level 1 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value		692
Level 1 | Equity Securities: Common/collective trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 1 | Fixed Income Securities: Common/collective trust [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 1 | Partnership and joint venture interests
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 1 | Other assets
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 2 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value		0
Level 2 | Equity Securities: Common/collective trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 2 | Fixed Income Securities: Common/collective trust [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 2 | Partnership and joint venture interests
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 2 | Other assets
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 3 | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value		0
Level 3 | Equity Securities: Common/collective trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 3 | Fixed Income Securities: Common/collective trust [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 3 | Partnership and joint venture interests
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	0	0
Level 3 | Other assets
Defined Benefit Plan Disclosure [Line Items]
Pension plans assets, fair value	$ 0	$ 0