SEGMENT INFORMATION (Revenues from External Customers and Segment Operating Profit Before Unallocated Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 313,525	$ 298,293	$ 283,832	$ 264,482	$ 260,253	$ 236,049	$ 217,781	$ 200,045	$ 1,160,132	$ 914,128	$ 730,027
Operating profit	$ 37,383	$ 33,902	$ 32,080	$ 30,331	$ 31,765	$ 27,776	$ 23,606	$ 22,820	133,696	105,967	86,183
Russia
Segment Reporting Information [Line Items]
Revenues									40,866	36,506	48,945
Operating Segments
Segment Reporting Information [Line Items]
Revenues									1,160,815	914,966	730,003
Operating profit									218,121	186,133	144,619
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenues									642,216	471,603	374,509
Operating profit									143,021	112,312	90,616
Operating Segments | Europe
Segment Reporting Information [Line Items]
Revenues									474,988	400,460	299,279
Operating profit									67,545	68,717	50,189
Operating Segments | Russia
Segment Reporting Information [Line Items]
Revenues									43,611	37,992	50,663
Operating profit									7,555	5,198	7,034
Operating Segments | Other
Segment Reporting Information [Line Items]
Revenues									0	4,911	5,552
Operating profit									$ 0	$ (94)	$ (3,220)