Derivative Financial Instruments (Narrative) (Details) (USD $)	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Derivative [Line Items]
Cash collateral received for derivative instruments	$ 1,370,000,000			$ 1,370,000,000			$ 2,580,000,000
Cash collateral provided for derivative instruments	4,320,000,000			4,320,000,000			3,360,000,000
Fair value of derivative liabilities	16,873,000,000	[1]		16,873,000,000	[1]		11,811,000,000	[1]
Maximum additional amount of payments related to termination events	110,000,000			110,000,000
Securities weighted average life (in years)				6 years 1 month 4 days			6 years 6 months
Other Comprehensive Income (Loss), Change in Unrealized Gain Loss on AFS Securities Designated as Fair Value Hedges, Net of Related Taxes	(14,000,000)		(1,000,000)	9,000,000		(61,000,000)
Fair Value Hedges | 1.35% Senior Note
Derivative [Line Items]
Fixed interest rate	1.35%			1.35%
Fair Value Hedges | 3.70% senior notes due in 2023
Derivative [Line Items]
Fixed interest rate	3.70%			3.70%
Cash Flow Hedges
Derivative [Line Items]
Securities weighted average life (in years)				1 month			10 months
Credit swap agreements
Derivative [Line Items]
Fair value of derivative liabilities	2,490,000,000			2,490,000,000
Maximum additional amount of payments related to termination events	$ 2,380,000,000			$ 2,380,000,000
Interest rate swap | Fair Value Hedges | 3.1% Subordinated Note
Derivative [Line Items]
Fixed interest rate	3.10%			3.10%
Interest rate swap | Fair Value Hedges | Senior notes
Derivative [Line Items]
Number of securities	2			2
Interest rate swap | Fair Value Hedges | Subordinated note
Derivative [Line Items]
Number of securities	1			1

[1] Amounts include all transactions regardless of whether or not they are subject to an enforceable netting arrangement.