NET INCOME PER SHARE - Tabular Disclosure (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings per share - basic
Net income	$ 16,251	$ 26,136	$ 18,616	$ 39,895
Undistributed earnings allocated to participating securities	72	5	79	4
Net income attributable to common stockholders - basic	$ 16,179	$ 26,131	$ 18,537	$ 39,891
Weighted average shares used in computing net income per share attributable to common stockholders - basic	151,712	147,648	151,497	141,524
Net income per share attributable to common stockholders - basic	$ 0.11	$ 0.18	$ 0.12	$ 0.28
Earnings per share - diluted
Net income attributable to common stockholders - diluted	$ 16,179	$ 26,131	$ 18,537	$ 39,891
Weighted average shares used in computing net income per share attributable to common stockholders - basic	151,712	147,648	151,497	141,524
Effect of dilutive securities	994	3,651	1,051	3,625
Weighted average shares used in computing diluted net income per share attributable to common stockholders - diluted	152,706	151,299	152,548	145,149
Net income per share attributable to common stockholders-diluted	$ 0.11	$ 0.17	$ 0.12	$ 0.27