NEW ACCOUNTING STANDARDS - CUMULATIVE EFFECT OF CHANGES DUE TO ADOPTION OF ASU 2014-09 (TABLES) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
ASSETS.
Prepaids and other current assets	$ 88,487	$ 74,768	$ 63,971
Deferred tax assets, net, noncurrent	15,523	16,018	12,012
LIABILITIES.
Deferred revenue	44,926	46,435	21,650
Retained earnings	$ 725,551	711,682	$ 721,664
Adjustment
ASSETS.
Prepaids and other current assets		10,797
Deferred tax assets, net, noncurrent		4,006
LIABILITIES.
Deferred revenue		24,785
Retained earnings		$ (9,982)

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards classified as noncurrent.

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