Loans Receivable And Allowance For Credit Losses (Recorded Investment Of Loans, Past Due) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Sep. 30, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	$ 25,733	$ 26,776
Financing receivable, 90 or More Days Delinquent	28,541	26,582
Financing receivable, Total Delinquent Loans	54,274	53,358
Financing receivable, Current Loans	5,186,273	5,111,841
Financing receivable, Total Recorded Investment	5,240,547	5,165,199
One-To Four-Family Loans - Originated [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	18,136	19,682
Financing receivable, 90 or More Days Delinquent	13,793	12,363
Financing receivable, Total Delinquent Loans	31,929	32,045
Financing receivable, Current Loans	4,449,883	4,362,498
Financing receivable, Total Recorded Investment	4,481,812	4,394,543
One-To Four-Family Loans - Purchased [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	6,854	6,243
Financing receivable, 90 or More Days Delinquent	14,220	13,836
Financing receivable, Total Delinquent Loans	21,074	20,079
Financing receivable, Current Loans	516,739	520,876
Financing receivable, Total Recorded Investment	537,813	540,955
Multi-Family And Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, Current Loans	53,538	57,936
Financing receivable, Total Recorded Investment	53,538	57,936
Consumer - Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	518	759
Financing receivable, 90 or More Days Delinquent	520	380
Financing receivable, Total Delinquent Loans	1,038	1,139
Financing receivable, Current Loans	158,991	163,402
Financing receivable, Total Recorded Investment	160,029	164,541
Consumer - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, 30 to 89 Days Delinquent	225	92
Financing receivable, 90 or More Days Delinquent	8	3
Financing receivable, Total Delinquent Loans	233	95
Financing receivable, Current Loans	7,122	7,129
Financing receivable, Total Recorded Investment	$ 7,355	$ 7,224