Debt (Details)	3 Months Ended			6 Months Ended		9 Months Ended			3 Months Ended
	Jun. 30, 2011 USD ($)	Sep. 30, 2010 USD ($)	Mar. 31, 2010 USD ($)	Jun. 30, 2011 USD ($)	Jun. 30, 2011 CNY	Sep. 30, 2010 USD ($)	Sep. 30, 2011 USD ($)	Dec. 31, 2010 USD ($)	Sep. 30, 2010 Notes 5.75% [Member] USD ($)	Sep. 30, 2010 Notes4.25% [Member] USD ($)	Sep. 30, 2010 Notes 6.2% [Member] USD ($)	Sep. 30, 2010 Notes 5.9% [Member] USD ($)
Fair value of long-term debt							$ 2,600,000,000	$ 2,400,000,000
Line of credit facility, maximum borrowing capacity	627,000,000			627,000,000	4,000,000,000		34,000,000
Line of credit facility number of installments				6	6
Line of credit facility final payment due, years from date of first advance	5
Repayment of debt			58,000,000			264,000,000
Redemption of principal			48,000,000
Interest rate on debt			6.25%						5.75%	4.25%	6.20%	5.90%
Par value of issued senior unsecured notes									400,000,000	300,000,000
Proceeds from issuance of long-term debt and capital securities, net									394,000,000	295,000,000
Net carrying amount of senior unsecured note debt		234,000,000
Repurchase of senior unsecured notes											126,000,000	100,000,000
Net loss on early redemption of senior unsecured notes		$ 30,000,000				$ 30,000,000
Maturity date			Feb. 18, 2010						Aug. 15, 2040	Aug. 15, 2020	Mar. 15, 2016	Mar. 15, 2014