Loans Receivable And Allowance For Credit Losses (Recorded Investment In Classified Loans) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	$ 5,650,554	$ 5,619,183
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	37,717	41,875
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	42,328	38,545
One-To Four-Family Loans - Originated [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	4,679,465	4,613,698
One-To Four-Family Loans - Originated [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	32,986	36,055
One-To Four-Family Loans - Originated [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	25,866	23,153
One-To Four-Family Loans - Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	759,825	790,073
One-To Four-Family Loans - Purchased [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	1,993	2,829
One-To Four-Family Loans - Purchased [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	15,440	14,538
Multi-Family And Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	60,717	59,562
Multi-Family And Commercial Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	2,612	2,578
Consumer - Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	144,121	149,321
Consumer - Home Equity [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	126	413
Consumer - Home Equity [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	935	815
Consumer - Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	6,426	6,529
Consumer - Other [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, Total Recorded Investment	$ 87	$ 39