Allowance for Loan Losses and Total Recorded Investment in HFI Loans (Details) - USD ($) $ in Millions	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	$ 22,134		$ 25,517
Allowance for loan losses for collectively reserved loans	1,665		2,434
Total allowance for loan losses	23,799	$ 25,819	27,951	$ 31,150	$ 31,820	$ 35,541
Recorded investment in individually impaired loans	164,931		172,169
Recorded investment in collectively reserved loans	2,878,830		2,863,543
Total recorded investment in loans	3,043,761		3,035,712
Single-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	22,075		25,437
Allowance for loan losses for collectively reserved loans	1,509		2,272
Total allowance for loan losses	23,584	25,597	27,709	30,876	31,514	35,177
Recorded investment in individually impaired loans	164,090		171,161
Recorded investment in collectively reserved loans	2,666,912		2,664,377
Total recorded investment in loans	2,831,002		2,835,538
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	59		80
Allowance for loan losses for collectively reserved loans	156		162
Total allowance for loan losses	215	$ 222	242	$ 274	$ 306	$ 364
Recorded investment in individually impaired loans	841		1,008
Recorded investment in collectively reserved loans	211,918		199,166
Total recorded investment in loans	$ 212,759		$ 200,174