Allowance for Loan Losses and Total Recorded Investment in HFI Loans (Details) - USD ($) $ in Millions	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	$ 28,745		$ 31,375
Allowance for loan losses for collectively reserved loans	2,405		4,166
Total allowance for loan losses	31,150	$ 31,820	35,541	$ 39,067	$ 41,911	$ 43,846
Recorded investment in individually impaired loans	179,873		188,186
Recorded investment in collectively reserved loans	2,851,776		2,859,608
Total recorded investment in loans	3,031,649		3,047,794
Single-family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	28,620		31,200
Allowance for loan losses for collectively reserved loans	2,256		3,977
Total allowance for loan losses	30,876	31,514	35,177	38,643	41,448	43,307
Recorded investment in individually impaired loans	178,504		186,377
Recorded investment in collectively reserved loans	2,654,896		2,672,184
Total recorded investment in loans	2,833,400		2,858,561
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	125		175
Allowance for loan losses for collectively reserved loans	149		189
Total allowance for loan losses	274	$ 306	364	$ 424	$ 463	$ 539
Recorded investment in individually impaired loans	1,369		1,809
Recorded investment in collectively reserved loans	196,880		187,424
Total recorded investment in loans	$ 198,249		$ 189,233