Consolidated Statements Of Stockholders' Equity (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, 2011	$ 1,939,529	$ 1,675	$ 1,392,567	$ (50,547)	$ 569,127	$ 26,707
Net income	74,513				74,513
Other comprehensive loss, net of tax	(2,500)					(2,500)
ESOP activity, net	6,406		3,434	2,972
Restricted stock activity, net	0	5	(5)
Stock-based compensation	1,196		1,196
Repurchase of common stock	(148,979)	(126)	(105,131)		(43,722)
Stock options exercised	61		61
Dividends on common stock to stockholders	(63,768)				(63,768)
Balance at Sep. 30, 2012	1,806,458	1,554	1,292,122	(47,575)	536,150	24,207
Net income	69,340				69,340
Other comprehensive loss, net of tax	(16,940)					(16,940)
ESOP activity, net	6,650		3,678	2,972
Restricted stock activity, net	172		172
Stock-based compensation	2,633		2,633
Repurchase of common stock	(89,375)	(76)	(62,836)		(26,463)
Stock options exercised	12		12
Dividends on common stock to stockholders	(146,824)				(146,824)
Balance at Sep. 30, 2013	1,632,126	1,478	1,235,781	(44,603)	432,203	7,267
Net income	77,694				77,694
Other comprehensive loss, net of tax	(281)					(281)
ESOP activity, net	2,014		362	1,652
Restricted stock activity, net	127		127
Stock-based compensation	2,134		2,134
Repurchase of common stock	(83,218)	(69)	(58,129)		(25,020)
Stock options exercised	458	1	457
Dividends on common stock to stockholders	(138,172)				(138,172)
Balance at Sep. 30, 2014	$ 1,492,882	$ 1,410	$ 1,180,732	$ (42,951)	$ 346,705	$ 6,986