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		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Consolidated Income Statement Data
NET REVENUES		$ 111,255	$ 101,625	$ 323,506	$ 287,232
COST OF REVENUES		55,542	51,783	163,870	145,117
PROVISION FOR INCOME TAXES		448	591	531	1,530
NET INCOME		$ 16,506	$ 12,809	$ 44,507	$ 34,595
Basic (in dollars per share)		$ 0.55	$ 0.44	$ 1.50	$ 1.20
Diluted (in dollars per share)	[1]	$ 0.54	$ 0.43	$ 1.46	$ 1.17
As Reported
Condensed Consolidated Income Statement Data
NET REVENUES			$ 103,790		$ 286,285
COST OF REVENUES			52,597		144,508
PROVISION FOR INCOME TAXES			586		1,514
NET INCOME			$ 14,165		$ 34,273
Basic (in dollars per share)			$ 0.49		$ 1.19
Diluted (in dollars per share)			$ 0.48		$ 1.16
Adjustments for Accounting Standards Update 2014-09
Condensed Consolidated Income Statement Data
NET REVENUES			$ (2,165)		$ 947
COST OF REVENUES			(814)		609
PROVISION FOR INCOME TAXES			5		16
NET INCOME			$ (1,356)		$ 322
Basic (in dollars per share)			$ (0.05)		$ 0.01
Diluted (in dollars per share)			$ (0.05)		$ 0.01

[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.