Allowance for Loan Losses and Reserve for Guaranty Losses Narratives (Details) (Consolidation Acounting Guidance Adopted on January 1, 2010 [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2010
Item Effected [Line Items]
Cumulative-effect adjustment, allowance for credit losses	$ 43,576	[1]
Net change in loss reserves	(3,500)
Cumulative-effect adjustment, reserve for guaranty losses	(54,103)
Interest Receivable [Member]
Item Effected [Line Items]
Cumulative-effect adjustment, allowance for credit losses	$ 7,000

[1] Upon recognition of the mortgage loans held by newly consolidated trusts and the associated accrued interest receivable at the transition date of our adoption of the consolidation accounting guidance on January 1, 2010, we increased our “Allowance for loan losses” by $43.6 billion, increased our “Allowance for accrued interest receivable” by $7.0 billion and decreased our “Reserve for guaranty losses” by $54.1 billion. The net decrease of $3.5 billion reflects the difference in the methodology used to estimate incurred losses for our allowance for loan losses and accrued interest receivable versus our reserve for guaranty losses.