OPERATING SEGMENTS - Revenues from External Customers and Segment Operating Profit Before Unallocated Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 264,482	$ 200,045
Operating profit	30,331	22,820
Russia
Segment Reporting Information [Line Items]
Revenues	8,952	7,259
Operating Segments
Segment Reporting Information [Line Items]
Revenues	264,814	200,194
Operating profit	48,647	38,680
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenues	147,490	100,269
Operating profit	30,655	24,068
Operating Segments | Europe
Segment Reporting Information [Line Items]
Revenues	107,843	91,152
Operating profit	16,832	15,340
Operating Segments | Russia
Segment Reporting Information [Line Items]
Revenues	9,481	7,513
Operating profit	1,160	(271)
Operating Segments | Other
Segment Reporting Information [Line Items]
Revenues	0	1,260
Operating profit	$ 0	$ (457)