Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017
Income Tax Examination [Line Items]
Write-down of deferred tax assets from revaluation of net operating losses due to change in federal tax rate									$ 3,400
Current income tax expense									328	$ 338
Income tax benefit	$ 747	$ 738	$ 627	$ 3,719	$ 769	$ 539	$ 605	$ 201	$ 5,830	$ 2,114
Effective income tax rate									32.20%	39.10%
ATM credits receivable	369								$ 369
Federal
Income Tax Examination [Line Items]
Income tax expense associated with current operations									2,400
Net operating losses	$ 23,800				$ 31,500				23,800	$ 31,500
Net operating losses utilized to offset taxes otherwise currently due									$ 7,700