Investments (Equity Method Investments, Statement of Operations) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	$ 2,983	$ 1,686	$ 1,066
Income (Loss) from Equity Method Investments Included Above	188	377	161
Income (Loss) from Equity Method Investments Not Included Above	34	40	61
Income (Loss) from Equity Method Investments	222	417	222
Real Estate Investment [Member]
Schedule Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	1,145	885	479
Securities Investment [Member]
Schedule Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	2,695	1,072	1,277
Other Investments [Member]
Schedule Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	716	654	591
Interest Expense [Member]
Schedule Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	(131)	(97)	(117)
Depreciation [Member]
Schedule Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	(7)	(3)	(8)
Management Fees Salary Expense [Member]
Schedule Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	(499)	(161)	(164)
Other Expense [Member]
Schedule Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	$ (936)	$ (664)	$ (992)