Assets And Liabilities Measured At Fair Value Realized Unrealized Gain Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gains (losses) on financial instruments, net	$ (25)	$ (73)
Fair Value Option Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gains (losses) on financial instruments, net	(10)	224
Exchangeable Senior Debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gains (losses) on financial instruments, net	(15)	(310)
Other Financial Instruments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized and unrealized gains (losses) on financial instruments, net	$ 0	$ 13