Loans Receivable And Allowance For Credit Losses (Recorded Investment Of Loans, Past Due) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	$ 23,225	$ 23,317
Financing receivable, 90 or More Days Delinquent	19,104	19,528
Financing receivable, Total Delinquent Loans	42,329	42,845
Financing receivable, Current Loans	5,608,225	5,576,338
Financing receivable, Total Recorded Investment	5,650,554	5,619,183
One-To Four-Family Loans - Originated [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	15,384	14,902
Financing receivable, 90 or More Days Delinquent	8,196	8,602
Financing receivable, Total Delinquent Loans	23,580	23,504
Financing receivable, Current Loans	4,655,885	4,590,194
Financing receivable, Total Recorded Investment	4,679,465	4,613,698
One-To Four-Family Loans - Purchased [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	6,687	7,788
Financing receivable, 90 or More Days Delinquent	10,475	10,530
Financing receivable, Total Delinquent Loans	17,162	18,318
Financing receivable, Current Loans	742,663	771,755
Financing receivable, Total Recorded Investment	759,825	790,073
Multi-Family And Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, Current Loans	60,717	59,562
Financing receivable, Total Recorded Investment	60,717	59,562
Consumer - Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	966	521
Financing receivable, 90 or More Days Delinquent	357	369
Financing receivable, Total Delinquent Loans	1,323	890
Financing receivable, Current Loans	142,798	148,431
Financing receivable, Total Recorded Investment	144,121	149,321
Consumer - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	188	106
Financing receivable, 90 or More Days Delinquent	76	27
Financing receivable, Total Delinquent Loans	264	133
Financing receivable, Current Loans	6,162	6,396
Financing receivable, Total Recorded Investment	$ 6,426	$ 6,529