Assets And Liabilities Measured At Fair Value Realized Unrealized Gain Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended			6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2012 Expedia [Member]	Jun. 30, 2013 Exchangeable Senior Debentures [Member]	Jun. 30, 2012 Exchangeable Senior Debentures [Member]	Jun. 30, 2013 Exchangeable Senior Debentures [Member]	Jun. 30, 2012 Exchangeable Senior Debentures [Member]	Jun. 30, 2013 Fair Value Opition Securities [Member]	Jun. 30, 2012 Fair Value Opition Securities [Member]	Jun. 30, 2013 Fair Value Opition Securities [Member]	Jun. 30, 2012 Fair Value Opition Securities [Member]	Jun. 30, 2013 Other Credit Derivatives [Member]	Jun. 30, 2012 Other Credit Derivatives [Member]		Jun. 30, 2013 Other Credit Derivatives [Member]	Jun. 30, 2012 Other Credit Derivatives [Member]
Realized and unrealized gains on financial instruments, net	$ 9	$ (160)	$ (64)	$ (178)		$ (106)	$ (35)	$ (416)	$ (217)	$ 112	$ 41	$ 336	$ 181	$ 3	$ (166)	[1]	$ 16	$ (142)	[1]
Forward Contract Indexed to Issuer's Equity, Shares					12
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 9	$ (160)	$ (64)	$ (178)		$ (106)	$ (35)	$ (416)	$ (217)	$ 112	$ 41	$ 336	$ 181	$ 3	$ (166)	[1]	$ 16	$ (142)	[1]

[1] In the first quarter of 2012, we entered into a forward contract to sell 12 million Expedia, Inc. shares at approximately $34 per share. The derivative contract was in a liability position in the prior year as the stock price of Expedia, Inc. shares had increased since the inception of the derivative contract and resulted in a recognition of unrealized losses on the contract in the prior year.