Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share
Net income	$ 19,983	$ 17,995	$ 57,484	$ 53,273
Income allocated to participating securities	(41)	(50)	(135)	(161)
Net income available to common stockholders	$ 19,942	$ 17,945	$ 57,349	$ 53,112
Total basic average common shares outstanding	138,331,681	143,262,534	140,246,658	145,518,110
Effect of dilutive stock options	2,723	790	1,136	112
Total diluted average common shares outstanding	138,334,404	143,263,324	140,247,794	145,518,222
Net earnings per share:
Basic	$ 0.14	$ 0.13	$ 0.41	$ 0.37
Diluted	$ 0.14	$ 0.13	$ 0.41	$ 0.37
Antidilutive stock options, excluded from the diluted average common shares outstanding calculation	2,052,485	2,444,932	2,064,175	2,465,393
Average Common Shares Outstanding [Member]
Earnings Per Share
Total basic average common shares outstanding	138,248,629	142,985,022	140,205,057	145,379,101
Average Committed ESOP Shares Outstanding [Member]
Earnings Per Share
Total basic average common shares outstanding	83,052	277,512	41,601	139,009