Allowance for Loan Losses and Total Recorded Investment in HFI Loans (Details) - USD ($) $ in Millions	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	$ 21,326		$ 25,517
Allowance for loan losses for collectively reserved loans	1,380		2,434
Total allowance for loan losses	22,706	$ 23,799	27,951	$ 29,135	$ 31,150	$ 35,541
Recorded investment in individually impaired loans	161,073		172,169
Recorded investment in collectively reserved loans	2,901,837		2,863,543
Total recorded investment in loans	3,062,910		3,035,712
Single-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	21,285		25,437
Allowance for loan losses for collectively reserved loans	1,231		2,272
Total allowance for loan losses	22,516	23,584	27,709	28,865	30,876	35,177
Recorded investment in individually impaired loans	160,307		171,161
Recorded investment in collectively reserved loans	2,678,498		2,664,377
Total recorded investment in loans	2,838,805		2,835,538
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	41		80
Allowance for loan losses for collectively reserved loans	149		162
Total allowance for loan losses	190	$ 215	242	$ 270	$ 274	$ 364
Recorded investment in individually impaired loans	766		1,008
Recorded investment in collectively reserved loans	223,339		199,166
Total recorded investment in loans	$ 224,105		$ 200,174