Allowance for Loan Losses Allowance Narrative (Details) (Interest Receivable [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fannie Mae [Member]
Allowance for Loan Losses [Line Items]
Allowance for Accrued Interest Receivable	$ 863	$ 1,100
Consolidated Trusts [Member]
Allowance for Loan Losses [Line Items]
Allowance for Accrued Interest Receivable	$ 81	$ 104