Summary of Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	$ 51		$ 51		$ 55
Current	124		124		139
Total	175		175		194
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract]
Cash and cash equivalents subject to project finance facilities and lease agreements	178		178		306
Held-to-maturity Securities, Restricted	25		25		25
Interest Costs Capitalized	9	4	17	11
Inventory	262		262		294
Treasury Stock, Value, Acquired, Cost Method			290
Adjustments Related to Tax Withholding for Share-based Compensation			5
Debt Service
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	42		42		42
Current	16		16		11
Total	58		58		53
Rent Reserve
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	0		0		0
Current	7		7		0
Total	7		7		0
Construction Major Maintenance
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	2		2		10
Current	47		47		33
Total	49		49		43
Security Project Insurance
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	5		5		0
Current	54		54		79
Total	59		59		79
Other
Restricted Cash and Cash Equivalents Items [Line Items]
Non-current	2		2		3
Current	0		0		16
Total	$ 2		$ 2		$ 19