Loans Receivable And Allowance For Credit Losses (Summary Of Loan Portfolio Segment Disaggregated By The Company's Impairment Method) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013
Financing Receivable, Impaired [Line Items]
Recorded investment in loans collectively evaluated for impairment	$ 6,033,282	$ 5,940,279
Recorded investment in loans individually evaluated for impairment	29,582	27,411
Financing receivable, Total Recorded Investment	6,062,864	5,967,690
ACL for loans collectively evaluated for impairment	8,967	8,822
One-To Four-Family Loans - Originated [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment in loans collectively evaluated for impairment	5,248,233	5,107,899
Recorded investment in loans individually evaluated for impairment	14,413	12,950
Financing receivable, Total Recorded Investment	5,262,646	5,120,849
ACL for loans collectively evaluated for impairment	6,737	5,771
One-To Four-Family Loans - Purchased [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment in loans collectively evaluated for impairment	594,105	634,705
Recorded investment in loans individually evaluated for impairment	14,565	13,882
Financing receivable, Total Recorded Investment	608,670	648,587
ACL for loans collectively evaluated for impairment	1,817	2,486
One-To Four-Family Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment in loans collectively evaluated for impairment	5,842,338	5,742,604
Recorded investment in loans individually evaluated for impairment	28,978	26,832
Financing receivable, Total Recorded Investment	5,871,316	5,769,436
ACL for loans collectively evaluated for impairment	8,554	8,257
Multi-Family And Commercial [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment in loans collectively evaluated for impairment	56,236	57,603
Financing receivable, Total Recorded Investment	56,236	57,603
ACL for loans collectively evaluated for impairment	143	185
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment in loans collectively evaluated for impairment	134,708	140,072
Recorded investment in loans individually evaluated for impairment	604	579
Financing receivable, Total Recorded Investment	135,312	140,651
ACL for loans collectively evaluated for impairment	$ 270	$ 380