EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income		$ 16,413	$ (7,587)	$ (10,409)	$ 12,200	$ 40,595	$ 1,288	$ 3,702	$ 52,963	$ 10,617	[1],[2],[3],[4]	$ 98,548	[1],[2],[3],[4]	$ 45,015	[1],[2],[3],[4]
Weighted-average common shares outstanding (shares)	[2]									78,564		77,431		76,343
Earnings per share, basic (dollars per share)		$ 0.21	$ (0.10)	$ (0.13)	$ 0.16	$ 0.52	$ 0.01	$ 0.05	$ 0.69	$ 0.14	[2]	$ 1.27	[2]	$ 0.59	[2]
Effective of dilutive securities (shares)										4,500		5,401		3,389
Weighted - average common shares outstanding, assuming dilution (shares)	[2]									83,064		82,832		79,732
Earnings per share, diluted (dollars per share)		$ 0.20	$ (0.10)	$ (0.13)	$ 0.15	$ 0.49	$ 0.01	$ 0.04	$ 0.65	$ 0.13	[2]	$ 1.19	[2]	$ 0.56	[2]
Outstanding anti-dilutive stock options and RSUs (shares)										188		221		322
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average effect of dilutive securities (shares)										2,891		3,471		2,025
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average effect of dilutive securities (shares)										1,609		1,930		1,364

[1] On January 1, 2018, the Company adopted the ASC 606 revenue recognition standard and adjusted prior periods to conform. See "Note 2. Significant Accounting Policies" for additional information.

[2] On January 1, 2018, the Company adopted the ASC 606 revenue recognition standard and adjusted prior periods to conform. See "Note 2. Significant Accounting Policies" for additional information.

[3] On January 1, 2018, the Company adopted the ASC 606 revenue recognition standard and adjusted prior periods to conform. See "Note 2. Significant Accounting Policies" for additional information.

[4] On January 1, 2018, the Company adopted the ASC 606 revenue recognition standard and adjusted prior periods to conform. See "Note 2. Significant Accounting Policies" for additional information.