Segment Reporting (Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 3,221,917	$ 3,248,176	$ 3,270,108
Consolidated Trusts [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	2,850,000	2,830,000	2,810,000
Operating Segments [Member] | Single-Family [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	34,911	43,512	41,206
Operating Segments [Member] | Multifamily [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	9,947	9,281	10,848
Operating Segments [Member] | Capital Markets [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	432,689	510,848	596,436
Reconciling Items [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 2,744,370	$ 2,684,535	$ 2,621,618