Benefits and Pension Plans - Fair Value (Details) - USD ($) $ in Thousands	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2017
Pensions and Other Postretirement Benefits
Fair value of plan assets	$ 8,168	$ 7,859	$ 9,855	$ 9,003
Equity securities
Pensions and Other Postretirement Benefits
Fair value of plan assets	3,986	3,474
Debt securities
Pensions and Other Postretirement Benefits
Fair value of plan assets	4,182	4,385
Quoted prices in active markets (Level 1)
Pensions and Other Postretirement Benefits
Fair value of plan assets	8,168	7,859
Quoted prices in active markets (Level 1) | Equity securities
Pensions and Other Postretirement Benefits
Fair value of plan assets	3,986	3,474
Quoted prices in active markets (Level 1) | Debt securities
Pensions and Other Postretirement Benefits
Fair value of plan assets	$ 4,182	$ 4,385