Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Current expense									$ 379	$ 328
Deferred expense									1,792	5,502
Total expense	$ 639	$ 325	$ 517	$ 690	$ 747	$ 738	$ 627	$ 3,719	$ 2,171	$ 5,830