Securities Available for Sale - Schedule of Unrealized Gains (Lossess) on Securities (Details) - Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance accumulated other comprehensive income	$ 5,534	$ 2,318
Net unrealized holding (loss) arising during the period	(21,468)	(11,915)
Reclassification adjustment for net gain (loss) realized in net income	0	(354)
Net change in unrealized (loss) before income taxes	(21,468)	(12,269)
Income tax benefit	8,158	4,662
Net change in unrealized (loss) on securities after taxes	(13,310)	(7,607)
Ending balance accumulated other comprehensive (loss)	$ (7,776)	$ (5,289)