Allowance for Loan Losses and Total Recorded Investment in HFI Loans (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	$ 20,768	$ 21,953
Allowance for loan losses for collectively reserved loans	1,361	1,512
Total allowance for loan losses	22,129	23,465	$ 25,819	$ 27,951
Recorded investment in individually impaired loans	151,205	156,187
Recorded investment in collectively reserved loans	2,971,245	2,939,629
Total recorded investment in loans	3,122,450	3,095,816
Single-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	20,731	21,920
Allowance for loan losses for collectively reserved loans	1,207	1,363
Total allowance for loan losses	21,938	23,283	25,597	27,709
Recorded investment in individually impaired loans	150,606	155,598
Recorded investment in collectively reserved loans	2,729,240	2,708,337
Total recorded investment in loans	2,879,846	2,863,935
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	37	33
Allowance for loan losses for collectively reserved loans	154	149
Total allowance for loan losses	191	182	$ 222	$ 242
Recorded investment in individually impaired loans	599	589
Recorded investment in collectively reserved loans	242,005	231,292
Total recorded investment in loans	$ 242,604	$ 231,881