Consolidated Statements Of Stockholders' Equity - 6 months ended Mar. 31, 2016 - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Unearned Compensation ESOP [Member]	Retained Earnings [Member]	AOCI [Member]
Balance at Sep. 30, 2015	$ 1,416,226	$ 1,371	$ 1,151,041	$ (41,299)	$ 296,739	$ 8,374
Net income	42,245				42,245
Other comprehensive loss, net of tax	(1,360)					(1,360)
ESOP activity, net	1,039		213	826
Restricted stock activity, net	32	$ 1	31
Stock-based compensation	783		783
Stock options exercised	299		299
Cash dividends to stockholders ($0.42 per share)	(55,856)				(55,856)
Balance at Mar. 31, 2016	$ 1,403,408	$ 1,372	$ 1,152,367	$ (40,473)	$ 283,128	$ 7,014