Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (24,007)		$ (20,030)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	1,308		1,056
Stock-based compensation	15,655		12,546
Amortization of acquired intangibles	352		352
Amortization of premiums/accretion of discounts on short-term investments	136		92
Allowance for doubtful debts	157		65
Excess tax deficiencies (benefits) from share-based compensation	4		(43)
Other	(172)		114
Changes in operating assets and liabilities:
Accounts receivable, net	17,324		14,016
Inventory	(45)		(296)
Prepaid expenses and other assets	(809)		(515)
Accounts payable	(2,302)		(1,812)
Accrued compensation and benefits	(3,064)		(1,268)
Accrued and other liabilities	(169)		79
Severance pay (net)	311		(64)
Deferred revenue	1,398		2,508
Deferred tax assets	(95)		4
Net cash provided by operating activities	5,982		6,804
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales/maturities of short-term investments	22,909		18,168
Purchase of short-term investments	(26,285)		(22,843)
Net purchases of property and equipment	(3,426)		(991)
Change in restricted cash	10		(11)
Net cash used in investing activities	(6,792)		(5,677)
CASH FLOWS FROM FINANCING ACTIVITIES:
Settlement of holdback liability	(7,157)
Proceeds from follow-on public offering, net of offering costs			127,854
Proceeds from issuance of common stock, net of repurchases	590		1,618
Shares withheld for tax withholding on vesting of restricted stock units	(2,352)		(2,137)
Excess tax (deficiencies) benefits from share-based compensation	(4)		43
Net cash (used in) provided by financing activities	(8,923)		127,378
Effect of exchange rate changes on cash and cash equivalents	172		(115)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(9,561)		128,390
CASH AND CASH EQUIVALENTS - Beginning of period	168,252	[1]	68,096
CASH AND CASH EQUIVALENTS - End of period	158,691		196,486
NONCASH INVESTING AND FINANCING ACTIVITIES:
Property and equipment incurred but not yet paid	$ 3,721		169
Vesting of restricted and early exercised stock options			$ 27

[1] The Condensed Consolidated Balance Sheet as of December 31, 2015 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements.