Business and Basis of Presentation - Reclassifications (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Schedule of Reclassifications [Line Items]
Selling	$ 95	$ 71	$ 160	$ 145
Cost of service	124	93	208	183
General & administrative	69	32	100	63
Total		196		391
As Previously Reported
Schedule of Reclassifications [Line Items]
Selling		91		185
Cost of service		74		145
General & administrative		31		61
Total		196		391
Reclassifications
Schedule of Reclassifications [Line Items]
Selling		(20)		(40)
Cost of service		19		38
General & administrative		1		2
Total		$ 0		$ 0