Goodwil and Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2019	Sep. 30, 2018
IntangibleAssets [Line Items]
Gross Carrying Amount	$ 41,625	$ 41,625
Accumulated Amortization	13,166	11,035
Intangible assets, net	28,459	30,590
Trademarks And Trade Names [Member]
IntangibleAssets [Line Items]
Gross Carrying Amount	5,084	5,084
Accumulated Amortization	1,053	831
Intangible assets, net	$ 4,031	$ 4,253
Trademarks And Trade Names [Member] | Maximum [Member]
IntangibleAssets [Line Items]
Estimated Useful Lives	20 years	20 years
Trademarks And Trade Names [Member] | Minimum [Member]
IntangibleAssets [Line Items]
Estimated Useful Lives	5 years	5 years
Technical Library [Member]
IntangibleAssets [Line Items]
Estimated Useful Lives	20 years	20 years
Gross Carrying Amount	$ 400	$ 400
Accumulated Amortization	111	101
Intangible assets, net	289	299
Customer Relationships [Member]
IntangibleAssets [Line Items]
Gross Carrying Amount	33,539	33,539
Accumulated Amortization	9,460	7,870
Intangible assets, net	$ 24,079	$ 25,669
Customer Relationships [Member] | Maximum [Member]
IntangibleAssets [Line Items]
Estimated Useful Lives	15 years	15 years
Customer Relationships [Member] | Minimum [Member]
IntangibleAssets [Line Items]
Estimated Useful Lives	6 years	6 years
Backlog [Member]
IntangibleAssets [Line Items]
Estimated Useful Lives	1 year	1 year
Gross Carrying Amount	$ 378	$ 378
Accumulated Amortization	358	176
Intangible assets, net	$ 20	$ 202
Non-competition arrangments [Member]
IntangibleAssets [Line Items]
Estimated Useful Lives	1 year	1 year
Gross Carrying Amount	$ 40	$ 40
Accumulated Amortization	5	1
Intangible assets, net	$ 35	$ 39
Construction Contract Value [Member]
IntangibleAssets [Line Items]
Estimated Useful Lives	1 year	1 year
Gross Carrying Amount	$ 2,184	$ 2,184
Accumulated Amortization	2,179	2,056
Intangible assets, net	$ 5	$ 128