Interim Pension and Other Postretirement Benefit Plan Information - Schedule of Assumptions Used (Details)			3 Months Ended			9 Months Ended
	Jun. 05, 2018	Mar. 01, 2018	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.29%	4.12%	4.29%	3.89%	3.73%	4.29%	3.73%
Rate of compensation increase			3.50%		3.50%	3.50%	3.50%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate			3.89%		3.73%	3.89%	3.73%
Rate of compensation increase			3.50%		3.50%	3.50%	3.50%
Expected return on plan assets			6.75%		7.00%	6.75%	7.00%
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate			3.89%		3.73%	3.89%	3.73%
Expected return on plan assets			4.29%		4.45%	4.29%	4.45%