Fair Value Of Financial Instruments (Schedule Of Carrying Amounts And Estimated Fair Values Of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012
Carrying Amount [Member]
Assets:
Cash and cash equivalents	$ 105,157	$ 141,705
HTM securities	1,902,228	1,887,947
Loans receivable	5,640,077	5,608,083
BOLI	58,394	58,012
Capital stock of FHLB	130,784	132,971
Liabilities:
Deposits	4,582,163	4,550,643
Advances from FHLB	2,532,493	2,530,322
Repurchase agreements	365,000	365,000
Estimated Fair Value [Member]
Assets:
Cash and cash equivalents	105,157	141,705
HTM securities	1,974,115	1,969,899
Loans receivable	5,996,716	5,978,872
BOLI	58,394	58,012
Capital stock of FHLB	130,784	132,971
Liabilities:
Deposits	4,633,035	4,607,732
Advances from FHLB	2,686,396	2,701,142
Repurchase agreements	$ 385,555	$ 388,761