Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Statement of Financial Position [Abstract]
Interest-earning deposits	$ 46,427	$ 198,809
Loans receivable, allowance for credit losses	$ 9,435	$ 9,226
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,400,000,000	1,400,000,000
Common stock, shares issued	141,502,665	141,440,030
Common stock, shares outstanding	141,502,665	141,440,030