INCOME TAXES (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Property and equipment	$ 203	$ 681
Intangible assets	1,525	1,428
Accrued expenses	9,172	10,729
Net operating loss carryforward	5,368	5,233
Deferred revenue	1,165	2,162
Stock-based compensation	19,701	12,484
Other assets	17	14
Deferred tax assets	37,151	32,731
Deferred tax liabilities:
Property and equipment	1,735	646
Intangible assets	4,969	1,598
Accrued revenue and expenses	500	511
Stock-based compensation	1,606	1,672
Other liabilities	314	912
Deferred tax liabilities	9,124	5,339
Net deferred tax assets	28,027	27,392
Deferred Tax Assets Classification
Deferred tax assets, current	0	11,847
Deferred tax assets, noncurrent	31,005	18,312
Deferred Tax Liabilities Classification
Deferred tax liabilities	0	365
Deferred tax liabilities, noncurrent	2,979	2,402
Business acquisitions
Deferred tax assets:
Stock-based compensation	$ 11,471	$ 7,219
Amortization period of stock-based compensation for tax	15 years