Stockholders' Equity - Narrative (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	May 31, 2015 EUR (€)	Feb. 13, 2015 USD ($)	May 31, 2014 EUR (€)	Aug. 02, 2013 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Preferred stock, shares authorized (in shares) | shares	300,000.0
Cash dividend declared (in dollars per share) | $ / shares	$ 2.86	$ 2.40	$ 2.07
Cash dividend paid (in dollars per share) | $ / shares	$ 2.73	$ 2.30	$ 2.005
Pre tax cumulative translation adjustment gains (losses) included in accumulated comprehensive income (loss)	$ (1,000,000,000)	$ (1,400,000,000)
Unrecognized pension and other postretirement benefits costs included in accumulated comprehensive income (loss)	291,000,000	405,000,000
Estimated unrecognized benefit cost that will be amortized from accumulated other comprehensive income into net periodic benefit cost next year	41,000,000
Net investment hedging
Defined Benefit Plan Disclosure [Line Items]
After tax cumulative translation adjustment gains (losses) included in accumulated comprehensive income (loss)	$ 81,000,000	$ 375,000,000
Euro notes, issued 2014 | Net investment hedging | Euro notes
Defined Benefit Plan Disclosure [Line Items]
Face value of notes | €						€ 1,000,000,000.0
Euro notes, issued 2015 | Net investment hedging | Euro notes
Defined Benefit Plan Disclosure [Line Items]
Face value of notes | €				€ 1,000,000,000.0
2013 Stock Repurchase Program
Defined Benefit Plan Disclosure [Line Items]
Authorized repurchase amount							$ 6,000,000,000
Shares repurchased (in shares) | shares			14,900,000
Average price of shares repurchased (in dollars per share) | $ / shares			$ 96.84
Authorized repurchases remaining			$ 0
2015 Stock Repurchase Program
Defined Benefit Plan Disclosure [Line Items]
Authorized repurchase amount					$ 6,000,000,000
Shares repurchased (in shares) | shares	7,100,000	18,700,000	6,100,000
Average price of shares repurchased (in dollars per share) | $ / shares	$ 140.56	$ 107.17	$ 91.78
Authorized repurchases remaining	$ 2,400,000,000