Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Intangible Assets
Useful life	15 years
Goodwill impairment charges	$ 0	$ 0	$ 0	$ 0
Change to goodwill	0	0	0
Amortization of customer relationships, patents, non-competes and other intangibles	255	527	$ 496
Total intangible assets, Gross Amount	6,191	10,221
Finite-lived intangible assets, Accumulated Amortization	(907)	(4,682)
Carrying Amount	5,284	5,539
Patents
Intangible Assets
Finite-lived intangible assets Gross Amount		4,030
Finite-lived intangible assets, Accumulated Amortization		(3,977)
Finite-lived intangible assets, Carrying Amount		53
Customer relationships
Intangible Assets
Finite-lived intangible assets Gross Amount	2,100	2,100
Finite-lived intangible assets, Accumulated Amortization	(718)	(574)
Finite-lived intangible assets, Carrying Amount	1,382	1,526
Other Intangible Assets
Intangible Assets
Finite-lived intangible assets Gross Amount	291	291
Finite-lived intangible assets, Accumulated Amortization	(189)	(131)
Finite-lived intangible assets, Carrying Amount	102	160
Trademarks
Intangible Assets
Indefinite-lived intangible assets	$ 3,800	$ 3,800