Defined Benefit Pension and Other Postretirement Plans - Narrative (Details) - USD ($)	9 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Pension Benefits
Defined Benefit Plan Disclosure
Contribution made to Pension Plan	$ 8,234,000	$ 10,079,000
Expected contribution to pensions plans in the remainder of current fiscal year	3,000,000
VEBA
Defined Benefit Plan Disclosure
Contribution made to Pension Plan	$ 0	$ 0

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration