Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Statement of Financial Position [Abstract]
Loans covered by FDIC loss share agreements	$ 80,137	$ 97,030
Loans and written loan commitments at fair value under the fair value option	1,156,442	1,118,687
Loans held for sale	21,301	9,867
Property held for sale	7,974	0
Property covered under FDIC loss share agreements	$ 50	$ 61
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	58,693,499	55,219,596
Common stock, shares outstanding	58,693,499	55,219,596