Employee Benefit Plans - Multi-Employer Plan (Details)	3 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) plan	Sep. 30, 2016 USD ($)	Jun. 30, 2012 USD ($) quarter	Jan. 05, 2015 USD ($)	Nov. 18, 2014 USD ($)
Multiemployer Plans [Line Items]
Multiemployer plans, number of plans | plan	2
Labor Management Pension Fund
Multiemployer Plans [Line Items]
Withdrawal obligation	$ 4,000,000		$ 4,300,000	$ 4,900,000	$ 4,400,000
Multiemployer plan, quarterly installments for withdrawal liability			$ 91,000
Multiemployer plan, quarterly installments for withdrawal liability, number of quarters | quarter			80
Multiemployer Plans, Pension | Multiemployer Plans, Defined Benefit Pension Plans [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, number of plans | plan	2
Other Postretirement Benefit Plan
Multiemployer Plans [Line Items]
Defined Benefit Plan, Service Cost	$ 152,000	$ 190,000
Multiemployer plans, number of plans | plan	10
Defined Benefit Plan, Interest Cost	$ 209,000	207,000
Defined Benefit Plan, Amortization of Gain (Loss)	(210,000)	(157,000)
Amortization of prior service credit	(439,000)	(439,000)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ (288,000)	$ (199,000)