Discontinued and Held-for-sale Operations (Held-for-sale Operations Recurring Fair Value) (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	$ 15,752	$ 14,178
Derivative Assets	668	2,298
Assets, Fair Value Disclosure	18,485	20,274
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(406)	(2,468)
Liabilities, Fair Value Disclosure	(406)	(2,468)
Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Assets, Fair Value Disclosure	445	1,031
Liabilities, Fair Value Disclosure	19	54
Foreign Government Debt Securities [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	306	303
Foreign Government Debt Securities [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	328	597
Corporate Debt Securities [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1,326	1,263
Corporate Debt Securities [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	93	76
Other Debt Obligations [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure		327
Interest Rate Contract [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	616	2,258
Interest Rate Contract [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	7	31
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	19	35
Foreign Exchange Contract [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	52	40
Foreign Exchange Contract [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	17
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		19
Fair Value, Inputs, Level 1 [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1,797	1,852
Derivative Assets	31	40
Assets, Fair Value Disclosure	1,828	1,995
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(14)	(13)
Liabilities, Fair Value Disclosure	(14)	(13)
Fair Value, Inputs, Level 1 [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Assets, Fair Value Disclosure	328	555
Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Government Debt Securities [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	3	3
Fair Value, Inputs, Level 1 [Member] | Foreign Government Debt Securities [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	328	555
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Other Debt Obligations [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure		0
Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	31	40
Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	0	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		0
Fair Value, Inputs, Level 2 [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	13,955	12,326
Derivative Assets	632	2,210
Assets, Fair Value Disclosure	15,596	17,125
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(392)	(2,452)
Liabilities, Fair Value Disclosure	(392)	(2,452)
Fair Value, Inputs, Level 2 [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Assets, Fair Value Disclosure	110	467
Liabilities, Fair Value Disclosure	11	25
Fair Value, Inputs, Level 2 [Member] | Foreign Government Debt Securities [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	303	300
Fair Value, Inputs, Level 2 [Member] | Foreign Government Debt Securities [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	42
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1,326	1,263
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	93	76
Fair Value, Inputs, Level 2 [Member] | Other Debt Obligations [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure		327
Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	580	2,170
Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	0	22
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	11	24
Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	52	40
Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	17
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		1
Fair Value, Inputs, Level 3 [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	0
Derivative Assets	5	48
Assets, Fair Value Disclosure	1,061	1,154
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	(3)
Liabilities, Fair Value Disclosure	0	(3)
Fair Value, Inputs, Level 3 [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Assets, Fair Value Disclosure	7	9
Liabilities, Fair Value Disclosure	8	29
Fair Value, Inputs, Level 3 [Member] | Foreign Government Debt Securities [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Government Debt Securities [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Other Debt Obligations [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Available-for-sale Securities, Fair Value Disclosure		0
Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	5	48
Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	7	9
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	8	11
Fair Value, Inputs, Level 3 [Member] | Foreign Exchange Contract [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Exchange Contract [Member] | Discontinued Operation Or Assets Disposal [Member]
Held-for-sale Operations Recurring Fair Value [Line Items]
Derivative Assets	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		$ 18