RECENT ACCOUNTING PRONOUNCEMENTS Lease Standard - Effect on Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Jan. 01, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, net	$ 1,221,769	$ 1,242,058
Prepaid expenses and other current assets	193,147	178,313
Total current assets	1,557,785	1,567,710
Revenue earning equipment, net	10,009,161	9,415,961
Operating property and equipment, net	871,524	862,054
Sales-type leases and other assets		967,800
Total assets	13,948,985	13,347,808
Short-term debt and current portion of long-term debt	1,117,489	937,131
Accrued expenses and other current liabilities	797,298	847,739
Total current liabilities	2,754,579	2,516,746
Long-term debt	6,025,679	5,712,146
Other non-current liabilities	1,399,273	1,402,625
Deferred income taxes		1,179,700
Total liabilities	11,382,181	10,811,240
Retained earnings	2,343,857	2,337,252
Accumulated other comprehensive loss	(890,418)	(911,634)
Total shareholders' equity	2,566,804	2,536,568	$ 2,473,975	$ 2,453,577
Total liabilities and shareholders' equity	13,948,985	13,347,808
Sales-type leases and other assets	$ 978,705	967,802
Accounting Standards Update 2016-02 | As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, net		1,219,400
Prepaid expenses and other current assets		201,600
Total current assets		1,568,400
Revenue earning equipment, net		9,498,000
Operating property and equipment, net		843,800
Sales-type leases and other assets		606,600
Total assets		13,051,100
Short-term debt and current portion of long-term debt		930,000
Accrued expenses and other current liabilities		630,500
Total current liabilities		2,292,300
Long-term debt		5,693,600
Other non-current liabilities		849,900
Deferred income taxes		1,304,800
Total liabilities		10,140,800
Retained earnings		2,710,700
Accumulated other comprehensive loss		(911,300)
Total shareholders' equity		2,910,300
Total liabilities and shareholders' equity		13,051,100
Accounting Standards Update 2016-02 | New Lease Standard Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings					$ 315,000
Lessor Adjustments | Accounting Standards Update 2016-02 | New Lease Standard Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, net		22,600
Prepaid expenses and other current assets		(23,300)
Total current assets		(700)
Revenue earning equipment, net		(84,200)
Operating property and equipment, net		0
Sales-type leases and other assets		156,800
Total assets		72,000
Short-term debt and current portion of long-term debt		0
Accrued expenses and other current liabilities		145,100
Total current liabilities		145,100
Long-term debt		0
Other non-current liabilities		421,200
Deferred income taxes		(124,600)
Total liabilities		441,700
Retained earnings		(369,600)
Accumulated other comprehensive loss		(100)
Total shareholders' equity		(369,700)
Total liabilities and shareholders' equity		72,000
Lessee Adjustments | Accounting Standards Update 2016-02 | New Lease Standard Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, net		0
Prepaid expenses and other current assets		0
Total current assets		0
Revenue earning equipment, net		2,200
Operating property and equipment, net		18,200
Sales-type leases and other assets		204,300
Total assets		224,700
Short-term debt and current portion of long-term debt		7,200
Accrued expenses and other current liabilities		72,200
Total current liabilities		79,300
Long-term debt		18,500
Other non-current liabilities		131,500
Deferred income taxes		(500)
Total liabilities		228,800
Retained earnings		(3,800)
Accumulated other comprehensive loss		(200)
Total shareholders' equity		(4,100)
Total liabilities and shareholders' equity		224,700
Prior Period Error | New Lease Standard Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Receivables, net		24,000
Revenue earning equipment, net		83,000
Sales-type leases and other assets		$ 65,000