ACQUISITIONS (Fair Values and Useful Lives of Intangible Assets Acquired) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Continuum
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired, amount	$ 14,450
Think
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired, amount	$ 6,882
Customer relationships | Continuum
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)	6 years 6 months 12 days
Finite-lived intangible assets acquired, amount	$ 5,800
Customer relationships | Think
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)	7 years
Finite-lived intangible assets acquired, amount	$ 6,117
Favorable lease | Continuum
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)	11 years 2 months
Finite-lived intangible assets acquired, amount	$ 5,500
Favorable lease | Think
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired, amount	$ 0
Contract royalties | Continuum
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)	8 years
Finite-lived intangible assets acquired, amount	$ 1,900
Contract royalties | Think
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired, amount	$ 0
Trade names | Continuum
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)	5 years
Finite-lived intangible assets acquired, amount	$ 1,250
Trade names | Think
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)	5 years
Finite-lived intangible assets acquired, amount	$ 765