Restructuring (Details) (Global Restructuring Plan 2012 [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2012 positions employees	Sep. 30, 2013 General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Number of Positions Eliminated	600
Restructuring and Related Cost, Expected Number of Contractor and Other Positions Eliminated	300
Restructuring and Related Cost, Cost Incurred to Date		$ 26
Restructuring Reserve, Accrual Adjustment		$ (4)