Fair Value (Fair Value Option - Fair Value and Principal Balances) (Details) (USD $) In Millions	Sep. 30, 2011		Dec. 31, 2010
Customer Resale Agreements [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	$ 802		$ 866
Aggregate unpaid principal balance of items for which fair value option was elected	748		806
Difference between fair value and aggregate unpaid principal balance	54		60
Residential Mortgage Backed Agency Hybrid Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	1,050	[1]
Aggregate unpaid principal balance of items for which fair value option was elected	856	[1]
Difference between fair value and aggregate unpaid principal balance	194	[1]
Residential Mortgage Loans Held For Sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	1,353		1,878
Aggregate unpaid principal balance of items for which fair value option was elected	1,301		1,882
Difference between fair value and aggregate unpaid principal balance	52		(4)
Residential Mortgage Loans Held For Sale [Member] | Performing Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	1,336		1,844
Aggregate unpaid principal balance of items for which fair value option was elected	1,280		1,839
Difference between fair value and aggregate unpaid principal balance	56		5
Residential Mortgage Loans Held For Sale [Member] | Loans 90 Days Or More Past Due [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	16		33
Aggregate unpaid principal balance of items for which fair value option was elected	19		41
Difference between fair value and aggregate unpaid principal balance	(3)		(8)
Residential Mortgage Loans Held For Sale [Member] | Nonaccrual Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	1		1
Aggregate unpaid principal balance of items for which fair value option was elected	2		2
Difference between fair value and aggregate unpaid principal balance	(1)		(1)
Commercial Mortgage Loans Held for Sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	831	[2]	877	[2]
Aggregate unpaid principal balance of items for which fair value option was elected	977	[2]	1,039	[2]
Difference between fair value and aggregate unpaid principal balance	(146)	[2]	(162)	[2]
Commercial Mortgage Loans Held for Sale [Member] | Performing Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	816	[2]	847	[2]
Aggregate unpaid principal balance of items for which fair value option was elected	949	[2]	990	[2]
Difference between fair value and aggregate unpaid principal balance	(133)	[2]	(143)	[2]
Commercial Mortgage Loans Held for Sale [Member] | Nonaccrual Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	15	[2]	30	[2]
Aggregate unpaid principal balance of items for which fair value option was elected	28	[2]	49	[2]
Difference between fair value and aggregate unpaid principal balance	(13)	[2]	(19)	[2]
Residential Mortgage Loans Portfolio [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	226		116
Aggregate unpaid principal balance of items for which fair value option was elected	370		142
Difference between fair value and aggregate unpaid principal balance	(144)		(26)
Residential Mortgage Loans Portfolio [Member] | Performing Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	65		36
Aggregate unpaid principal balance of items for which fair value option was elected	84		44
Difference between fair value and aggregate unpaid principal balance	(19)		(8)
Residential Mortgage Loans Portfolio [Member] | Loans 90 Days Or More Past Due [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	88	[3]	64	[3]
Aggregate unpaid principal balance of items for which fair value option was elected	95	[3]	67	[3]
Difference between fair value and aggregate unpaid principal balance	(7)	[3]	(3)	[3]
Residential Mortgage Loans Portfolio [Member] | Nonaccrual Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value of items for which fair value option was elected	73		16
Aggregate unpaid principal balance of items for which fair value option was elected	191		31
Difference between fair value and aggregate unpaid principal balance	$ (118)		$ (15)

[1] These residential mortgage-backed agency hybrid securities are carried as Trading securities.

[2] There were no loans 90 days or more past due within this category at September 30, 2011 or December 31, 2010.

[3] The majority of these loans are government insured loans, which positively impacts the fair value.