ACQUISITIONS AND DISPOSALS (Schedule of Pro Forma Results) (Details) - Pro Forma - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition And Disposal Group, Pro Forma Information [Abstract]
Net revenue	$ 794,037	$ 660,130
Net income (loss)	$ 163,611	$ (9,340)
Basic net income (loss) per share attributable to common stockholders (in dollars per share)	$ 2.00	$ (0.12)
Diluted net income (loss) per share attributable to common stockholders (in dollars per share)	$ 1.88	$ (0.12)
Nowait, Inc
Business Acquisition, Pro Forma Information [Abstract]
Net revenue	$ 847,587	$ 717,140
Net income (loss)	$ 151,817	$ (12,141)
Basic net income (loss) per share attributable to common stockholders (in dollars per share)	$ 1.86	$ (0.16)
Diluted net income (loss) per share attributable to common stockholders (in dollars per share)	$ 1.74	$ (0.16)
Turnstyle Analytics Inc
Business Acquisition, Pro Forma Information [Abstract]
Net revenue	$ 847,172	$ 714,132
Net income (loss)	$ 152,713	$ (6,741)
Basic net income (loss) per share attributable to common stockholders (in dollars per share)	$ 1.87	$ (0.09)
Diluted net income (loss) per share attributable to common stockholders (in dollars per share)	$ 1.75	$ (0.09)
Eat 24
Disposal Group, Pro Forma Information [Abstract]
Net revenue	$ 792,904	$ 654,996
Net income	$ 164,799	$ 203
Basic net income per share attributable to common stockholders (in dollars per share)	$ 2.02	$ 0.00
Diluted net income per share attributable to common stockholders (in dollars per share)	$ 1.89	$ 0.00