NET INCOME (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic net income (loss) per share
Net income (loss)	$ 48,270	$ (15,992)	$ 61,046	$ (69,392)
Denominator (in shares)	63,917	62,997	63,714	62,556
Basic net income (loss) per share (in dollars per share)	$ 0.76	$ (0.25)	$ 0.96	$ (1.11)
Add effect of diluted securities:
Add: Interest Expense on convertible debt, net of tax	$ 5,340	$ 0	$ 15,815	$ 0
Stock options and equivalents and convertible debt (in shares)	18,773	0	18,568	0
Denominator for diluted (loss) income per share (in shares)	82,690	62,997	82,282	62,556
Diluted net income (loss) per share (in dollars per share)	$ 0.65	$ (0.25)	$ 0.93	$ (1.11)
Potentially dilutive common shares:
Total potentially dilutive common shares (in shares)			3,359	25,324
Convertible debt
Potentially dilutive common shares:
Total potentially dilutive common shares (in shares)			0	17,931
Stock options and equivalents
Potentially dilutive common shares:
Total potentially dilutive common shares (in shares)			3,359	7,393