Debt - Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2016	Nov. 30, 2016	Dec. 31, 2015	May 31, 2015	May 31, 2014	Feb. 28, 2014	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009	Dec. 31, 2005
Debt Instrument [Line Items]
Long-term debt including current maturities	$ 7,827		$ 6,897
Long-term debt including current maturities, fair value	8,281		7,153
Less: Current maturities of long-term debt	(650)		(1)
Long-term debt, excluding current maturities	7,177		6,896
Other borrowings
Debt Instrument [Line Items]
Long-term debt including current maturities	6		6
Long-term debt including current maturities, fair value	$ 6		6
0.90% notes due February 25, 2017 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	0.90%					0.90%
Effective interest rate	0.95%
Long-term debt including current maturities	$ 650		649
Long-term debt including current maturities, fair value	$ 650		649
1.95% notes due March 1, 2019 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	1.95%					1.95%
Effective interest rate	1.98%
Long-term debt including current maturities	$ 648		647
Long-term debt including current maturities, fair value	$ 656		655
6.25% notes due April 1, 2019 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	6.25%								6.25%
Effective interest rate	6.25%
Long-term debt including current maturities	$ 698		698
Long-term debt including current maturities, fair value	$ 768		790
4.88% notes due thru December 31, 2020 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	4.88%									4.88%
Effective interest rate	4.96%
Long-term debt including current maturities	$ 4		4
Long-term debt including current maturities, fair value	$ 4		4
3.375% notes due September 15, 2021 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	3.375%							3.375%
Effective interest rate	3.43%
Long-term debt including current maturities	$ 348		347
Long-term debt including current maturities, fair value	$ 365		362
1.75% Euro notes due May 20, 2022 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	1.75%				1.75%
Effective interest rate	1.86%
Long-term debt including current maturities	$ 520		536
Long-term debt including current maturities, fair value	$ 565		564
1.25% Euro notes due May 22, 2023 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	1.25%			1.25%
Effective interest rate	1.35%
Long-term debt including current maturities	$ 520		536
Long-term debt including current maturities, fair value	$ 549		538
3.50% notes due March 1, 2024 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	3.50%					3.50%
Effective interest rate	3.54%
Long-term debt including current maturities	$ 695		695
Long-term debt including current maturities, fair value	$ 728		727
2.65% notes due November 15, 2026 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	2.65%	2.65%
Effective interest rate	2.69%
Long-term debt including current maturities	$ 991		0
Long-term debt including current maturities, fair value	$ 959		0
2.125% Euro notes due May 22, 3030 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	2.125%			2.125%
Effective interest rate	2.18%
Long-term debt including current maturities	$ 519		536
Long-term debt including current maturities, fair value	$ 565		530
3.0% Euro notes due May 19, 2034 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	3.00%				3.00%
Effective interest rate	3.13%
Long-term debt including current maturities	$ 512		528
Long-term debt including current maturities, fair value	$ 618		569
4.875% notes due September 15, 2041 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	4.875%							4.875%
Effective interest rate	4.97%
Long-term debt including current maturities	$ 636		635
Long-term debt including current maturities, fair value	$ 734		708
3.9% notes due September 1, 2042 | Unsecured debt
Debt Instrument [Line Items]
Interest rate, stated percentage	3.90%						3.90%
Effective interest rate	3.96%
Long-term debt including current maturities	$ 1,080		1,080
Long-term debt including current maturities, fair value	$ 1,114		$ 1,051