Allowance for Loan Losses and Total Recorded Investment in HFI Loans (Details) - USD ($) $ in Millions	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	$ 19,238		$ 21,953
Allowance for loan losses for collectively reserved loans	1,161		1,512
Total allowance for loan losses	20,399	$ 22,129	23,465	$ 23,799	$ 25,819	$ 27,951
Recorded investment in individually impaired loans	145,320		156,187
Recorded investment in collectively reserved loans	2,991,409		2,939,629
Total recorded investment in loans	3,136,729		3,095,816
Single-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	19,197		21,920
Allowance for loan losses for collectively reserved loans	1,021		1,363
Total allowance for loan losses	20,218	21,938	23,283	23,584	25,597	27,709
Recorded investment in individually impaired loans	144,833		155,598
Recorded investment in collectively reserved loans	2,745,268		2,708,337
Total recorded investment in loans	2,890,101		2,863,935
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	41		33
Allowance for loan losses for collectively reserved loans	140		149
Total allowance for loan losses	181	$ 191	182	$ 215	$ 222	$ 242
Recorded investment in individually impaired loans	487		589
Recorded investment in collectively reserved loans	246,141		231,292
Total recorded investment in loans	$ 246,628		$ 231,881