OPERATING SEGMENTS (Revenues from External Customers and Segment Operating Profit Before Unallocated Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 260,253	$ 236,049	$ 217,781	$ 200,045	$ 202,184	$ 192,764	$ 174,695	$ 160,384	$ 914,128	$ 730,027	$ 555,117
Operating profit	$ 31,765	$ 27,776	$ 23,606	$ 22,820	$ 24,015	$ 21,835	$ 18,476	$ 21,857	105,967	86,183	76,493
Russia
Segment Reporting Information [Line Items]
Revenues									36,506	48,945	53,328
Operating Segments
Segment Reporting Information [Line Items]
Revenues									914,966	730,003	555,043
Operating profit									186,133	144,619	109,308
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenues									471,603	374,509	284,636
Operating profit									112,312	90,616	66,814
Operating Segments | Europe
Segment Reporting Information [Line Items]
Revenues									400,460	299,279	204,150
Operating profit									68,717	50,189	34,573
Operating Segments | Russia
Segment Reporting Information [Line Items]
Revenues									37,992	50,663	55,764
Operating profit									5,198	7,034	7,077
Operating Segments | Other
Segment Reporting Information [Line Items]
Revenues									4,911	5,552	10,493
Operating profit									$ (94)	$ (3,220)	$ 844