Advances Narrative (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Advances [Line Items]
Callable Federal Home Loan Bank Advances	$ 112,214		$ 112,214		$ 121,123
Putable Federal Home Loan Bank Advances	1,653,471		1,653,471		2,572,471
Percent Of Fixed Rate Advances Swapped To Adjustable Rate	33.00%		33.00%		42.00%
Prepayment Fees on Advances Received	74,234	23,526	84,238	29,309
Deferred Prepayment Fees on Advances During Period	$ 258	$ 254	$ 504	$ 686
Maximum [Member]
Advances [Line Items]
Federal Home Loan Bank Advances, Interest Rate	8.61%		8.61%		8.61%
Minimum [Member]
Advances [Line Items]
Federal Home Loan Bank Advances, Interest Rate	0.04%		0.04%		0.04%