Pension Plans - Percentage of Total Plan Assets (Details) - Pension Plan	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Asset Category	100.00%	100.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Asset Category	33.00%	32.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Asset Category	34.00%	46.00%
Commodity Option
Defined Benefit Plan Disclosure [Line Items]
Asset Category	11.00%	2.00%
Insurance Company
Defined Benefit Plan Disclosure [Line Items]
Asset Category	13.00%	12.00%
Options
Defined Benefit Plan Disclosure [Line Items]
Asset Category	1.00%	0.00%
Cash
Defined Benefit Plan Disclosure [Line Items]
Asset Category	8.00%	8.00%