Segment Reporting (Assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 3,248,176	$ 3,270,108	$ 3,222,422
Single-Family [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	43,512	41,206	17,595
Multifamily [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	9,281	10,848	5,182
Capital Markets [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	510,848	596,436	723,217
Consolidated Trusts [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	2,827,565	2,812,459	2,749,571
Eliminations/Adjustments [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (143,030)	$ (190,841)	$ (273,143)