Supporting Financial Information - Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Sep. 30, 2017
Finite Lived Intangible Assets [Roll Forward]
Goodwill, net	$ 25,989		$ 25,989	$ 25,989
Intangible assets, including goodwill, gross balance				43,612
Accumulated amortization finite-lived intangibles, beginning balance			(2,496)
Current period amortization	(400)	$ (400)	(881)
Accumulated amortization finite-lived intangibles, ending balance	(3,377)		(3,377)
Finite-lived intangibles, net balance	14,246		14,246
Intangible assets, including goodwill, net balance	40,235		$ 40,235
Estimated useful live of finite-lived intangible assets			10 years
Customer Relationships [Member]
Finite Lived Intangible Assets [Roll Forward]
Finite-lived intangible assets, gross balance				16,626
Accumulated amortization finite-lived intangibles, beginning balance			$ (2,355)
Current period amortization			(831)
Accumulated amortization finite-lived intangibles, ending balance	(3,186)		(3,186)
Finite-lived intangibles, net balance	13,440		13,440
Noncompete Agreements [Member]
Finite Lived Intangible Assets [Roll Forward]
Finite-lived intangible assets, gross balance				480
Accumulated amortization finite-lived intangibles, beginning balance			(68)
Current period amortization			(24)
Accumulated amortization finite-lived intangibles, ending balance	(92)		(92)
Finite-lived intangibles, net balance	388		388
Trade Names [Member]
Finite Lived Intangible Assets [Roll Forward]
Finite-lived intangible assets, gross balance				$ 517
Accumulated amortization finite-lived intangibles, beginning balance			(73)
Current period amortization			(26)
Accumulated amortization finite-lived intangibles, ending balance	(99)		(99)
Finite-lived intangibles, net balance	$ 418		$ 418