Marketable Securities, at Fair Value (Tables)

12 Months Ended

Dec. 31, 2011

Investments, Debt and Equity Securities [Abstract]

Schedule of Realized Gain (Loss) on Available-for-sale Securities

Realized gains (losses) are as follows:

	Year Ended December 31,
	2011	2010	2009
	(In $ millions)
Realized gain on sale of securities	—	8	5
Realized loss on sale of securities	—	—	—
Net realized gain (loss) on sale of securities	—	8	5

Schedule of Available-for-sale Securities Reconciliation

The amortized cost, gross unrealized gain, gross unrealized loss and fair values for available-for-sale securities by major security type are as follows:

	Amortized Cost	Gross Unrealized Gain	Gross Unrealized Loss	Fair Value
	(In $ millions)
Mutual funds	64	—	—	64
As of December 31, 2011	64	—	—	64
US corporate debt securities	1	—	—	1
Mutual funds	77	—	—	77
As of December 31, 2010	78	—	—	78