Supporting Financial Information - Intangible Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 17,623	$ 17,623
Less accumulated amortization	(4,258)	(2,496)
Intangible assets, net	$ 13,365	15,127
Finite-lived intangibles estimated useful lives	10 years
Amortization expense of intangibles	$ 1,800	1,400
Customer contracts and related customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	16,626	16,626
Less accumulated amortization	(4,018)	(2,355)
Covenants not to compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	480	480
Less accumulated amortization	(116)	(68)
Trade name
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	517	517
Less accumulated amortization	$ (124)	$ (73)