Premises and Equipment - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 142,333	$ 149,262
Accumulated depreciation	(30,124)	(30,756)
Premise and equipment, net	112,209	118,506
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	25,973	26,591
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	89,927	94,306
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	26,160	27,597
Construction in progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 273	$ 768