Other Assets (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Other current assets
Unamortized cash retention awards	$ 148	$ 125
Prepayments and accrued income	58	73
Derivatives	17	17
Debt issuance costs	8	8
Income tax receivable	42	69
Other Receivables	54	48
Total other current assets	327	340
Other non-current assets
Unamortized cash retention awards	145	48
Deferred compensation plan assets	115	114
Prepayments and accrued income	17
Debt issuance costs	19	27
Derivatives	33	30
Income Taxes Receivable, Noncurrent	11
Other receivables	25	14
Total other non-current assets	365	233
Total other assets	$ 692	$ 573