SEGMENT INFORMATION - Summary (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 833,164	$ 962,240	$ 1,628,141	$ 1,882,002
Operating income (loss) for segments	190,737	131,852	346,907	236,822
Depreciation and amortization	123,648	107,280	245,392	216,314
Corporate
Segment Reporting Information [Line Items]
Operating income (loss) for segments	(58,706)	(63,532)	(122,262)	(126,906)
Depreciation and amortization	1,714	2,030	3,555	3,504
Acquisition-related costs	8,100	21,900	26,400	48,000
North America
Segment Reporting Information [Line Items]
Revenues	621,801		1,215,830
North America \| Operating segments
Segment Reporting Information [Line Items]
Revenues	621,801	710,965	1,215,830	1,398,009
Operating income (loss) for segments	147,184	112,176	272,588	206,259
Depreciation and amortization	105,433	89,455	207,958	182,163
Europe
Segment Reporting Information [Line Items]
Revenues	155,631		298,908
Europe \| Operating segments
Segment Reporting Information [Line Items]
Revenues	155,631	186,506	298,908	352,054
Operating income (loss) for segments	82,682	65,673	153,230	120,180
Depreciation and amortization	11,775	11,487	24,520	23,063
Asia-Pacific
Segment Reporting Information [Line Items]
Revenues	55,732		113,403
Asia-Pacific \| Operating segments
Segment Reporting Information [Line Items]
Revenues	55,732	64,769	113,403	131,939
Operating income (loss) for segments	19,577	17,535	43,351	37,289
Depreciation and amortization	$ 4,726	$ 4,308	$ 9,359	$ 7,584

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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