SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNITNG PRONOUNCEMENTS Prior Period Income Statement Adjustments, Adoption of ASU 2014-09 (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Condensed Consolidated Income Statement Data
NET REVENUES		$ 107,563	$ 97,571	$ 212,251	$ 185,607
COST OF REVENUES		54,116	49,786	108,328	93,334
PROVISION FOR INCOME TAXES		760	604	83	939
NET INCOME		$ 13,902	$ 11,407	$ 28,001	$ 21,786
Basic (in dollars per share)		$ 0.47	$ 0.40	$ 0.95	$ 0.76
Diluted (in dollars per share)	[1]	$ 0.46	$ 0.39	$ 0.92	$ 0.74
As Reported
Condensed Consolidated Income Statement Data
NET REVENUES			$ 97,169		$ 182,495
COST OF REVENUES			49,532		91,911
PROVISION FOR INCOME TAXES			598		928
NET INCOME			$ 11,265		$ 20,108
Basic (in dollars per share)			$ 0.39		$ 0.70
Diluted (in dollars per share)			$ 0.38		$ 0.68
Adjustments for Accounting Standards Update 2014-09
Condensed Consolidated Income Statement Data
NET REVENUES			$ 402		$ 3,112
COST OF REVENUES			254		1,423
PROVISION FOR INCOME TAXES			6		11
NET INCOME			$ 142		$ 1,678
Basic (in dollars per share)			$ 0.01		$ 0.06
Diluted (in dollars per share)			$ 0.01		$ 0.06

[1] The Company includes the shares underlying performance-based awards in the calculation of diluted earnings per share if the performance conditions have been satisfied as of the end of the reporting period and excludes such shares when the necessary conditions have not been met. The Company has excluded the shares underlying the outstanding performance-based awards in the 2017 and 2016 calculations as the shares were not contingently issuable as of the end of the reporting periods.