NET INCOME PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings per share - basic
Net income	$ 26,136	$ 23,630	$ 39,895	$ 38,187
Undistributed earnings allocated to participating securities	5		4
Net income attributable to common stockholders - basic	$ 26,131	$ 23,630	$ 39,891	$ 38,187
Weighted average shares used in computing basic net income per share attributable to common stockholders - basic	147,648	134,523	141,524	134,585
Net income per share attributable to common stockholders - basic	$ 0.18	$ 0.18	$ 0.28	$ 0.28
Earnings per share - diluted
Net income attributable to common stockholders - diluted	$ 26,131	$ 23,630	$ 39,891	$ 38,187
Weighted average shares used in computing basic net income per share attributable to common stockholders - basic	147,648	134,523	141,524	134,585
Effect of dilutive securities	3,651	2,291	3,625	1,050
Weighted average shares used in computing diluted net income per share attributable to common stockholders - diluted	151,299	136,814	145,149	135,635
Net income per share attributable to common stockholders-diluted	$ 0.17	$ 0.17	$ 0.27	$ 0.28