Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Current portion of long-term debt, including capital leases	$ 613,781	$ 598,583
Short-term debt and current portion of long-term debt	791,410	634,530
Total before fair market value adjustment	5,226,756	5,476,656
Fair market value adjustment on notes subject to hedging (3)	1,110	5,253
Debt issuance costs	(14,221)	(15,229)
Total after fair market value adjustment	5,213,645	5,466,680
Long-term debt	4,599,864	4,868,097
Total debt	$ 5,391,274	$ 5,502,627
Short-term debt
Short-term Debt [Line Items]
Short-term debt, Weighted-Average interest rate	1.07%	2.26%
Short-term debt	$ 177,629	$ 35,947
U.S. commercial paper
Short-term Debt [Line Items]
Weighted-Average interest rate	0.87%	0.55%
Commercial paper	$ 342,480	$ 547,130
Global revolving credit facility
Short-term Debt [Line Items]
Weighted-Average interest rate	2.06%	2.31%
Global revolving credit facility	$ 4,703	$ 25,291
Unsecured U.S. notes – Medium-term notes
Short-term Debt [Line Items]
Weighted-Average interest rate	2.67%	2.84%
Unsecured U.S. notes - Medium-term notes	$ 4,113,421	$ 4,112,519
Unsecured U.S. obligations, principally bank term loans
Short-term Debt [Line Items]
Weighted-Average interest rate	2.19%	1.73%
Unsecured U.S. obligations, principally bank term loans	$ 50,000	$ 50,000
Unsecured foreign obligations
Short-term Debt [Line Items]
Weighted-Average interest rate	1.55%	1.92%
Unsecured foreign obligations	$ 232,092	$ 275,661
Asset-Backed US Obligations
Short-term Debt [Line Items]
Weighted-Average interest rate	1.80%	1.81%
Unsecured foreign obligations	$ 459,876	$ 434,001
Capital lease obligations
Short-term Debt [Line Items]
Weighted-Average interest rate	3.17%	3.31%
Capital lease obligations	$ 24,184	$ 32,054