GOODWILL - Roll Forward (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($)
Goodwill [Roll Forward]
Balance as of January 1, 2016	$ 115,930
Effect of net foreign currency exchange rate changes	(373)
Balance as of September 30, 2016	111,722
North America
Goodwill [Roll Forward]
Balance as of January 1, 2016	81,464
Effect of net foreign currency exchange rate changes	111
Balance as of September 30, 2016	77,476
Europe
Goodwill [Roll Forward]
Balance as of January 1, 2016	34,466
Effect of net foreign currency exchange rate changes	(484)
Balance as of September 30, 2016	34,246
NavigationArts
Goodwill [Roll Forward]
Purchase accounting adjustments	2,030
NavigationArts | North America
Goodwill [Roll Forward]
Purchase accounting adjustments	2,030
NavigationArts | Europe
Goodwill [Roll Forward]
Purchase accounting adjustments	0
AGS
Goodwill [Roll Forward]
Purchase accounting adjustments	(8,737)
AGS | North America
Goodwill [Roll Forward]
Purchase accounting adjustments	(8,737)
AGS | Europe
Goodwill [Roll Forward]
Purchase accounting adjustments	0
Other Acquisitions
Goodwill [Roll Forward]
Purchase accounting adjustments	291
Acquisition	2,581
Other Acquisitions | North America
Goodwill [Roll Forward]
Purchase accounting adjustments	204
Acquisition	2,404
Other Acquisitions | Europe
Goodwill [Roll Forward]
Purchase accounting adjustments	87
Acquisition	$ 177