Accumulated Other Comprehensive Income (Loss) - Narrative (Details) $ in Millions	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	May 31, 2015 EUR (€)	May 31, 2014 EUR (€)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative translation adjustment losses, net of tax	$ 1,100		$ 1,100
Unrecognized pension and other postretirement benefits costs, net of tax	385		$ 365
Net Investment Hedging | Euro Notes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income related to net investment hedge unrealized gain	195	$ 375
Euro Notes Issued May 2015 | Net Investment Hedging | Euro Notes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Face value of notes | €				€ 1,000,000,000
Long-term debt	1,100
Euro Notes Issued May 2014 | Net Investment Hedging | Euro Notes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Face value of notes | €					€ 1,000,000,000
Long-term debt	$ 1,100