Transactions with Stockholders (Details) (USD $)	Mar. 31, 2013		Dec. 31, 2012
Schedule of Other Transactions [Line Items]
Advances	$ 58,282,314,000		$ 53,943,961,000
Loans And Leases Receivable, Unpaid Principal Balance	7,041,859,000		7,366,141,000
Notional Amount of Derivatives	8,972,421,000		12,159,963,000
Director [Member]
Schedule of Other Transactions [Line Items]
Advances	869,000,000		948,000,000
Federal Home Loan Bank Advances, Percent of Principal	1.50%	[1]	1.80%	[1]
Loans And Leases Receivable, Unpaid Principal Balance	35,000,000		41,000,000
Federal Home Loan Bank, Mortgage Purchase Program, Unpaid Principal Balance, Percent of Total	0.50%	[1]	0.60%	[1]
Mortgage-backed Securities	0		0
Mortgage-backed Securities, Percent of Total	0.00%	[1]	0.00%	[1]
Regulatory Capital Stock, Value	230,000,000		229,000,000
Regulatory Capital Stock, Percent of Total	5.00%	[1]	5.40%	[1]
Notional Amount of Derivatives	$ 0		$ 0
Derivative Notional Amount, Percent	0.00%	[1]	0.00%	[1]

[1] Percentage of total principal (Advances), unpaid principal balance (MPP), principal balance (mortgage-backed securities), regulatory capital stock, and notional balances (derivatives).