Allowance for Loan Losses Allowance at Recorded Investment (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	$ 44,786	[1]	$ 45,034	[1]
Allowance for loan losses for collectively reserved loans	11,675		13,761
Allowance for loan losses	56,461		58,795		70,109	72,156
Recorded investment in individually impaired loans	195,116	[1],[2]	200,391	[1],[2]
Recorded investment in collectively reserved loans	2,817,319	[2]	2,807,080	[2]
Total recorded investment	3,012,435	[2]	3,007,471	[2]
Single-Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	44,281	[1]	44,545	[1]
Allowance for loan losses for collectively reserved loans	11,220		13,142
Allowance for loan losses	55,501		57,687		68,738	70,633
Recorded investment in individually impaired loans	191,073	[1],[2]	195,852	[1],[2]
Recorded investment in collectively reserved loans	2,631,140	[2]	2,620,568	[2]
Total recorded investment	2,822,213	[2]	2,816,420	[2]
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses for individually impaired loans	505	[1]	489	[1]
Allowance for loan losses for collectively reserved loans	455		619
Allowance for loan losses	960		1,108		1,371	1,523
Recorded investment in individually impaired loans	4,043	[1],[2]	4,539	[1],[2]
Recorded investment in collectively reserved loans	186,179	[2]	186,512	[2]
Total recorded investment	$ 190,222	[2],[3],[4]	$ 191,051	[2],[3],[4]

[1] Includes acquired credit-impaired loans.

[2] Recorded investment consists of unpaid principal balance, unamortized premiums, discounts and other cost basis adjustments, and accrued interest receivable.

[3] Green (loan with acceptable risk); yellow (loan with signs of potential weakness); orange (loan with a well defined weakness that may jeopardize the timely full repayment); and red (loan with a weakness that makes timely collection or liquidation in full more questionable based on existing conditions and values).

[4] Multifamily loans 60-89 days delinquent are included in the seriously delinquent column.