SEGMENTS INFORMATION - Revenues from External Customers and Operating Profit/(Loss) Before Unallocated Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Operating profit	$ 64,560	$ 49,248	$ 167,494	$ 120,896
North America
Segment Reporting Information [Line Items]
Segment revenues	280,838	206,389	769,137	578,717
Operating profit	60,763	45,529	155,944	126,243
Europe
Segment Reporting Information [Line Items]
Segment revenues	171,482	157,446	516,320	431,472
Operating profit	28,871	25,984	84,329	66,453
Russia
Segment Reporting Information [Line Items]
Segment revenues	16,208	14,455	53,374	41,825
Operating profit	543	1,685	8,211	7,129
Operating Segments
Segment Reporting Information [Line Items]
Segment revenues	468,528	378,290	1,338,831	1,052,014
Operating profit	$ 90,177	$ 73,198	$ 248,484	$ 199,825