Capital lease obligation (Details) - USD ($) $ in Thousands	Jan. 01, 2015	Sep. 30, 2015	Sep. 30, 2014
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Less current obligation		$ 468
Long Term Obligations
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Present value of net minimum capital lease payments		4,380
Long-term obligations
Future capital lease rental payments		4,380
Environmental post-closure monitoring and maintenance activities		749	$ 823
Less amounts due within one year		(555)	(78)
Long-term obligations (less current portion)		4,574	$ 745
La Porte
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2016		468
2017		534
2018		538
2019		545
2020		550
Thereafter		8,122
Total minimum capital lease payments		10,757
Less amounts representing interest		(6,377)
Present value of net minimum capital lease payments		4,380
Less current obligation		(468)
Total long term capital lease obligation		3,912
Long-term obligations
Future capital lease rental payments		$ 4,380
La Porte | Property Plant And Equipment
Lease Term	20 years