Fair Value Measurements - Summary of Valuation Techniques and Significant Unobservable Inputs Used to Measure Level 3 Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Sep. 30, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Property held for sale	$ 3,216	$ 1,104
Fair value, measurements, nonrecurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	31,834	22,225
Impaired loans	200,312	188,017
Fair value, measurements, nonrecurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	31,834	22,225
Impaired loans	200,312	$ 188,017
Property held for sale	$ 3,216