Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]
Beginning balance at Dec. 31, 2011	$ 79,568	$ 2	$ 147,085	$ (66,130)	$ (616)	$ (773)
Beginning balance, shares at Dec. 31, 2011		22,978,166
Issuance of common stock upon exercise of stock options	3,093		3,093
Issuance of common stock upon exercise of stock options, shares	1,272,941	1,272,940
Vesting of restricted stock	881		881
Stock-based compensation	5,968		5,968
Issuance of common stock in connection with employee stock purchase plan	1,117		1,117
Issuance of common stock in connection with employee stock purchase plan, shares		44,970
Income tax benefit from employee stock option exercises	19		19
(Purchase) Sale of additional ownership interest in Incapsula, Inc.			(174)			174
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	227				227
Change in unrealized gain (loss) on derivatives	1,250				1,250
Net loss	(7,892)			(7,387)		(505)
Comprehensive loss	(6,415)
Ending balance at Dec. 31, 2012	84,231	2	157,989	(73,517)	861	(1,104)
Ending balance, shares at Dec. 31, 2012		24,296,076
Issuance of common stock, net of repurchases	3,544		3,544
Issuance of common stock upon exercise of stock options, shares	687,719
Issuance of common stock, net of repurchases, shares		806,226
Vesting of restricted stock	801		801
Stock-based compensation	22,494		22,494
Issuance of common stock in connection with employee stock purchase plan	2,772		2,772
Issuance of common stock in connection with employee stock purchase plan, shares		96,502
Exercise of warrant, shares		7,694
(Purchase) Sale of additional ownership interest in Incapsula, Inc.			357			(357)
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	(172)				(172)
Change in unrealized gain (loss) on derivatives	(1,117)				(1,117)
Net loss	(26,331)			(25,178)		(1,153)
Comprehensive loss	(27,620)
Ending balance at Dec. 31, 2013	86,222	2	187,957	(98,695)	(428)	(2,614)
Ending balance, shares at Dec. 31, 2013		25,206,498
Issuance of common stock related to acquisitions	24,163		24,163
Issuance of common stock related to acquisitions, shares		738,479
Issuance of common stock, net of repurchases	5,297		5,297
Issuance of common stock upon exercise of stock options, shares	496,297
Issuance of common stock, net of repurchases, shares		672,832
Vesting of restricted stock	454		454
Stock-based compensation	37,273		37,273
Issuance of common stock in connection with employee stock purchase plan	3,332		3,332
Issuance of common stock in connection with employee stock purchase plan, shares		188,068
Income tax benefit from employee stock option exercises	385		385
Pre-combination service relating to acquired Skyfence option plan	354		354
(Purchase) Sale of additional ownership interest in Incapsula, Inc.		89,603	(2,827)			2,827
Components of other comprehensive income (loss), net of tax
Change in unrealized gain (loss) on investments	(59)				(59)
Change in unrealized gain (loss) on derivatives	(1,002)				(1,002)
Net loss	(59,176)			(58,963)		(213)
Comprehensive loss	(60,237)
Ending balance at Dec. 31, 2014	$ 97,243	$ 2	$ 256,388	$ (157,658)	$ (1,489)
Ending balance, shares at Dec. 31, 2014		26,895,480