DEBT - Schedule of Debt (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Short-term debt and current portion of long-term debt:
Short-term debt, weighted-average interest rate	1.46%	2.69%
Short-term debt	$ 210,185,000	$ 81,522,000
Current portion of long-term debt, including finance leases	907,304,000	855,609,000
Total short-term debt and current portion of long-term debt	1,117,489,000	937,131,000
Long-term debt:
Commercial paper	800,000,000	578,000,000
Total long-term debt	6,954,080,000	6,585,843,000
Debt issuance costs	(21,097,000)	(18,088,000)
Total after fair market value adjustment	6,932,983,000	6,567,755,000
Current portion of long-term debt, including finance leases	(907,304,000)	(855,609,000)
Long-term debt	6,025,679,000	5,712,146,000
Total debt	7,143,168,000	6,649,277,000
Unamortized original issue discounts	7,000,000
Fair market value adjustment on notes subject to hedging	6,000,000	10,000,000
Aggregate notional amount of interest rate swaps	$ 725,000,000	$ 825,000,000
U.S. commercial paper
Long-term debt:
Long-term debt, weighted-average interest rate	2.76%	2.78%
Commercial paper	$ 695,272,000	$ 454,397,000
Canadian commercial paper
Long-term debt:
Long-term debt, weighted-average interest rate	1.99%	2.28%
Commercial paper	$ 105,169,000	$ 123,491,000
Trade receivables program
Long-term debt:
Long-term debt, weighted-average interest rate	0.00%	3.15%
Trade receivables program	$ 0	$ 200,000,000
Global revolving credit facility
Long-term debt:
Long-term debt, weighted-average interest rate	2.28%	2.25%
Global revolving credit facility	$ 13,224,000	$ 12,581,000
Unsecured U.S. notes — Medium-term notes
Long-term debt:
Long-term debt, weighted-average interest rate	3.30%	3.22%
Unsecured U.S. notes - Medium-term notes	$ 5,207,369,000	$ 4,853,496,000
Unsecured U.S. obligations
Long-term debt:
Long-term debt, weighted-average interest rate	3.49%	3.50%
Unsecured U.S. obligations	$ 250,000,000	$ 50,000,000
Unsecured foreign obligations
Long-term debt:
Long-term debt, weighted-average interest rate	2.67%	1.61%
Obligations	$ 33,710,000	$ 216,719,000
Asset-backed U.S. obligations
Long-term debt:
Long-term debt, weighted-average interest rate	2.36%	2.37%
Obligations	$ 605,634,000	$ 627,707,000
Finance lease obligations
Long-term debt:
Long-term debt, weighted-average interest rate	8.32%	7.97%
Finance lease obligations	$ 43,702,000	$ 47,452,000