Premises and Equipment - Schedule of Premises and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 149,262	$ 134,167
Accumulated depreciation	(30,756)	(36,617)
Premise and equipment, net	118,506	97,550
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	26,591	21,708
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	94,306	82,796
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	27,597	28,861
Construction in progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 768	$ 802