Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Current portion of long-term debt, including capital leases	$ 598,583	$ 32,511
Short-term debt and current portion of long-term debt	634,530	36,284
Total before fair market value adjustment	5,476,656	4,722,016
Fair market value adjustment on notes subject to hedging(3)	5,253	4,830
Total after fair market value adjustment	5,481,909	4,726,846
Long-term debt	4,883,326	4,694,335
Total debt	$ 5,517,856	$ 4,730,619
Short-term debt
Short-term Debt [Line Items]
Short-term debt, Weighted-Average Interest Rate	2.26%	1.30%
Short-term debt	$ 35,947	$ 3,773
U.S. commercial paper
Short-term Debt [Line Items]
Long-term debt, Weighted-Average Interest Rate	0.55%	0.35%
Commercial paper	$ 547,130	$ 276,694
Global revolving credit facility
Short-term Debt [Line Items]
Long-term debt, Weighted-Average Interest Rate	2.31%	1.60%
Global revolving credit facility	$ 25,291	$ 11,190
Unsecured U.S. notes – Medium-term notes
Short-term Debt [Line Items]
Long-term debt, Weighted-Average Interest Rate	2.84%	3.29%
Unsecured U.S. notes - Medium-term notes	$ 4,112,519	$ 3,772,159
Unsecured U.S. obligations, principally bank term loans
Short-term Debt [Line Items]
Long-term debt, Weighted-Average Interest Rate	1.73%	0.76%
Unsecured U.S. obligations, principally bank term loans	$ 50,000	$ 110,500
Unsecured foreign obligations
Short-term Debt [Line Items]
Long-term debt, Weighted-Average Interest Rate	1.92%	2.01%
Unsecured foreign obligations	$ 275,661	$ 295,776
Asset-Backed US Obligations [Member]
Short-term Debt [Line Items]
Long-term debt, Weighted-Average Interest Rate	1.81%	1.81%
Unsecured foreign obligations	$ 434,001	$ 218,137
Capital lease obligations
Short-term Debt [Line Items]
Long-term debt, Weighted-Average Interest Rate	3.31%	3.65%
Capital Lease Obligations	$ 32,054	$ 37,560