Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ (99)
Foreign currency translation adjustment	(129)	(2)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax	(8)	0
Income tax expense on amortization of postretirement benefit plan items	(1)
Unrealized loss on foreign exchange agreements	5
Ending balance	(233)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	145
Foreign currency translation adjustment	(129)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax	(8)
Income tax expense on amortization of postretirement benefit plan items	0
Unrealized loss on foreign exchange agreements	0
Ending balance	8
Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(231)
Foreign currency translation adjustment	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax	0
Income tax expense on amortization of postretirement benefit plan items	(1)
Unrealized loss on foreign exchange agreements	0
Ending balance	(228)
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(13)
Foreign currency translation adjustment	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax	0
Income tax expense on amortization of postretirement benefit plan items	0
Unrealized loss on foreign exchange agreements	5
Ending balance	(13)
Cost of revenue
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net actuarial loss on postretirement benefit plans into:	1
Reclassification of unrealized gain (loss) on foreign exchange agreements	1
Cost of revenue | Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net actuarial loss on postretirement benefit plans into:	0
Reclassification of unrealized gain (loss) on foreign exchange agreements	0
Cost of revenue | Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net actuarial loss on postretirement benefit plans into:	1
Reclassification of unrealized gain (loss) on foreign exchange agreements	0
Cost of revenue | Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net actuarial loss on postretirement benefit plans into:	0
Reclassification of unrealized gain (loss) on foreign exchange agreements	1
Selling, general and administrative expenses
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net actuarial loss on postretirement benefit plans into:	3
Selling, general and administrative expenses | Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net actuarial loss on postretirement benefit plans into:	0
Selling, general and administrative expenses | Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net actuarial loss on postretirement benefit plans into:	3
Selling, general and administrative expenses | Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of net actuarial loss on postretirement benefit plans into:	0
Revenue
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification of unrealized gain (loss) on foreign exchange agreements	(4)
Revenue | Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification of unrealized gain (loss) on foreign exchange agreements	0
Revenue | Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification of unrealized gain (loss) on foreign exchange agreements	0
Revenue | Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification of unrealized gain (loss) on foreign exchange agreements	$ (4)