Recast Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 62,190	$ 49,431	$ 115,718	$ 89,024
Cost of revenues	6,440	4,881	12,882	9,574
Gross profit	55,750	44,550	102,836	79,450
Research and development	17,717	11,498	33,259	21,907
Sales and marketing	41,349	32,580	81,321	63,494
General and administrative	7,989	6,579	15,058	12,088
Total operating expenses	67,055	50,657	129,638	97,489
Operating loss	(11,305)	(6,107)	(26,802)	(18,039)
Financial income (expenses), net	(811)	950	167	1,419
Loss before income taxes	(12,116)	(5,157)	(26,635)	(16,620)
Income taxes	(567)	(580)	(1,094)	(780)
Net loss	(12,683)	(5,737)	(27,729)	(17,400)
Prepaid expenses and other current assets	16,927		16,927		$ 14,346
Other assets	7,724		7,724		7,243
Deferred revenues	71,663		71,663		73,493
Deferred revenues	6,274		6,274		6,608
Other liabilities	7,933		7,933		7,807
Accumulated deficit	(137,119)		(137,119)		(109,390)
Amortization of deferred commissions			6,441	6,041
Deferred commissions			(5,824)	(5,902)
Deferred revenues			(2,164)	838
Other long term liabilities			126	(732)
Net cash provided by operating activities			20,383	7,384
As Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		50,174		90,554
Cost of revenues		4,878		9,550
Gross profit		45,296		81,004
Research and development		11,498		21,907
Sales and marketing		32,560		63,371
General and administrative		6,582		12,095
Total operating expenses		50,640		97,373
Operating loss		(5,344)		(16,369)
Financial income (expenses), net		950		1,419
Loss before income taxes		(4,394)		(14,950)
Income taxes		(641)		(964)
Net loss		(5,035)		(15,914)
Prepaid expenses and other current assets					7,130
Other assets					973
Deferred revenues					73,891
Deferred revenues					7,034
Other liabilities					6,561
Accumulated deficit					(122,454)
Amortization of deferred commissions				0
Deferred commissions				0
Deferred revenues				(694)
Other long term liabilities				(547)
Net cash provided by operating activities				7,384
Adjustments | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		(743)		(1,530)	(1,974)
Cost of revenues		3		24
Gross profit		(746)		(1,554)
Research and development		0		0
Sales and marketing		20		123
General and administrative		(3)		(7)
Total operating expenses		17		116
Operating loss		(763)		(1,670)
Financial income (expenses), net		0		0
Loss before income taxes		(763)		(1,670)
Income taxes		61		184
Net loss		(702)		(1,486)
Prepaid expenses and other current assets					7,216
Other assets					6,270
Deferred revenues					(398)
Deferred revenues					(426)
Other liabilities					1,246
Accumulated deficit					$ 13,064
Amortization of deferred commissions				6,041
Deferred commissions				(5,902)
Deferred revenues				1,532
Other long term liabilities				(185)
Net cash provided by operating activities				0
Licenses
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	33,460	27,310	58,534	45,402
Licenses | As Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		28,420		47,575
Licenses | Adjustments | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		(1,110)		(2,173)
Maintenance and services
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 28,730	22,121	$ 57,184	43,622
Maintenance and services | As Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		21,754		42,979
Maintenance and services | Adjustments | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		$ 367		$ 643