Defined Benefit Pension and Other Postretirement Plans - Narrative (Details) - USD ($)	6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans
Contribution made to Pension and Post-retirement Plans	$ 5,700,000	$ 4,900,000
Expected contribution to pension plan during remainder of fiscal year	5,500,000
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans
Contribution made to Pension and Post-retirement Plans	$ 0	$ 0