SEGMENT REPORTING (Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property and equipment, net	$ 83,303	$ 84,496
Goodwill	1,611,535	1,283,457	$ 1,254,866
Reconciliation of operating segment assets to total assets [Abstract]
Total assets	3,312,957	2,873,441
Reconciliation of operating segment liabilities to total liabilities [Abstract]
Total liabilities	291,015	222,191
North America [Member]
Segment Reporting Information [Line Items]
Property and equipment, net	79,493	79,736
Goodwill	1,573,088	1,253,494	1,227,777
Reconciliation of operating segment assets to total assets [Abstract]
Total assets	3,253,035	2,816,156
Reconciliation of operating segment liabilities to total liabilities [Abstract]
Total liabilities	272,776	201,831
International [Member]
Segment Reporting Information [Line Items]
Property and equipment, net	3,810	4,760
Goodwill	38,447	29,963	$ 27,089
Reconciliation of operating segment assets to total assets [Abstract]
Total assets	59,922	57,285
Reconciliation of operating segment liabilities to total liabilities [Abstract]
Total liabilities	$ 18,239	$ 20,360