Fair Value (Fair Value Option for Certain Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Option, Quantitative Disclosures [Line Items]
Carrying value at estimated fair value	$ 57,703	$ 56,592
Carrying value at estimated fair value	18,653	19,062
Consolidated Securitization Entities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Unpaid principal balance	1,528	2,539
Difference between estimated fair value and unpaid principal balance	70	127
Carrying value at estimated fair value	1,598	2,666
Loans in non-accrual status	0	0
Loans more than 90 days past due	0	0
Loans in non-accrual status or more than 90 days past due, or both - difference between aggregate estimated fair value and unpaid principal balance	0	0
Contractual principal balance	1,445	2,430
Difference between estimated fair value and contractual principal balance	10	97
Carrying value at estimated fair value	1,455	2,527
Residential Mortgage Loans - FVO [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Unpaid principal balance	508	0
Difference between estimated fair value and unpaid principal balance	(170)	0
Carrying value at estimated fair value	338	0
Loans in non-accrual status	0	0
Loans more than 90 days past due	81	0
Loans in non-accrual status or more than 90 days past due, or both - difference between aggregate estimated fair value and unpaid principal balance	$ (82)	$ 0