ACQUISITIONS (Fair Values and Useful Lives of Intangible Assets Acquired) (Details) - 2015 Acquisitions $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
NavigationArts
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired, amount	$ 2,800
AGS
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired, amount	$ 22,700
Customer relationships | NavigationArts
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)	10 years
Finite-lived intangible assets acquired, amount	$ 2,800
Customer relationships | AGS
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)	10 years
Finite-lived intangible assets acquired, amount	$ 22,700