Goodwill and Intangible Assets (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2013
Finite Lived Intangible Assets [Line Items]
Impairment of goodwill		$ 0	$ 0	$ 0
Amortization of intangible assets		352,000	435,000	779,000
Cash received from amended supply agreement		2,333,000	2,333,000	10,000,000
Other current assets		$ 2,457,000	3,916,000
Deferred credit amortization period		4 years
Gains in other income		$ 2,029,000	2,402,000	$ 1,522,000
General Electric Company
Finite Lived Intangible Assets [Line Items]
Cash received from amended supply agreement	$ 10,000,000
Additional amount paid on execution of agreement		$ 7,000,000
Acquired finite-lived intangible assets, period		3 years
Other current assets		$ 2,300,000
Deferred credit					$ 8,100,000
Other Income | General Electric Company
Finite Lived Intangible Assets [Line Items]
Gains in other income		$ 2,000,000	$ 2,000,000
Purchased Technology | Minimum
Finite Lived Intangible Assets [Line Items]
Useful life of intangible asset		6 years
Purchased Technology | Maximum
Finite Lived Intangible Assets [Line Items]
Useful life of intangible asset		7 years
Supply Agreement
Finite Lived Intangible Assets [Line Items]
Useful life of intangible asset		15 years