NET INCOME (LOSS) PER SHARE (Schedule of Basic and Diluted Net Loss Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share Reconciliation [Line Items]
Net income attributable to common stockholders		$ 7,947		$ 10,724
Basic Shares:
Number of shares used in basic calculation (in shares)	[1]	82,259	77,521	81,041	76,627
Basic net income per share attributable to common stockholders (in USD per share)	[1]	$ 0.10	$ 0.03	$ 0.13	$ (0.17)
Numerator:
Allocation of undistributed earnings for basic computation		$ 7,947		$ 10,724
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares		0
Reallocation of undistributed earnings to Class B shares		0
Allocation of undistributed earnings		$ 7,947		$ 10,724
Denominator:
Number of shares used in basic calculation (in shares)	[1]	82,259	77,521	81,041	76,627
Weighted-average effect of dilutive securities
Weighted-average effect of dilutive securities Conversion of Class B to Class A shares (in shares)		0
Stock options (in shares)		3,253		3,179
Restricted stock units (in shares)		1,921		1,877
Number of shares used in diluted calculation (in shares)	[1]	87,433	82,917	86,097	76,627
Diluted net income per share attributable to common stockholders (in USD per share)	[1]	$ 0.09	$ 0.02	$ 0.12	$ (0.17)
Common Class A
Earnings Per Share Reconciliation [Line Items]
Net income attributable to common stockholders			$ 1,869		$ (11,639)
Basic Shares:
Number of shares used in basic calculation (in shares)			69,978		68,961
Basic net income per share attributable to common stockholders (in USD per share)			$ 0.03		$ (0.17)
Numerator:
Allocation of undistributed earnings for basic computation			$ 1,869		$ (11,639)
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares			201
Reallocation of undistributed earnings to Class B shares			0
Allocation of undistributed earnings			$ 2,070		$ (11,639)
Denominator:
Number of shares used in basic calculation (in shares)			69,978		68,961
Weighted-average effect of dilutive securities
Weighted-average effect of dilutive securities Conversion of Class B to Class A shares (in shares)			7,543
Stock options (in shares)			3,526		0
Restricted stock units (in shares)			1,870		0
Number of shares used in diluted calculation (in shares)			82,917		68,961
Diluted net income per share attributable to common stockholders (in USD per share)			$ 0.02		$ (0.17)
Common Class B
Earnings Per Share Reconciliation [Line Items]
Net income attributable to common stockholders			$ 201		$ (1,294)
Basic Shares:
Number of shares used in basic calculation (in shares)			7,543		7,666
Basic net income per share attributable to common stockholders (in USD per share)			$ 0.03		$ (0.17)
Numerator:
Allocation of undistributed earnings for basic computation			$ 201		$ (1,294)
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares			0
Reallocation of undistributed earnings to Class B shares			39
Allocation of undistributed earnings			$ 240		$ (1,294)
Denominator:
Number of shares used in basic calculation (in shares)			7,543		7,666
Weighted-average effect of dilutive securities
Weighted-average effect of dilutive securities Conversion of Class B to Class A shares (in shares)			0
Stock options (in shares)			2,246		0
Restricted stock units (in shares)			0		0
Number of shares used in diluted calculation (in shares)			9,789		7,666
Diluted net income per share attributable to common stockholders (in USD per share)			$ 0.02		$ (0.17)

[1] The structure of the Company’s common stock changed during the year ended December 31, 2016. Refer to Note 13 for details.