Commitments and Contingencies (Tables)

12 Months Ended

Sep. 30, 2017

Commitments and Contingencies Disclosure [Abstract]

Summary of Asset Retirement Obligation Activity

The following table summarizes ARO activity:

Asset Retirement Obligations	September 30,
(in thousands)	2017
Balance at September 30, 2016	$	1,618
Accretion expense	65
Revision in estimated cash flows	(45		)
Balance at September 30, 2017	$	1,638