Description of Business and Basis of Presentation - Summary of Unaudited Consolidated Statement of Operations Reflecting Adoption of Topic 606 (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue:
Subscription and support	$ 43,200	$ 31,554
Professional services and other	4,791	2,918
Total revenue	47,991	34,472
Cost of revenue:
Professional services and other	3,594	2,575
Gross profit	34,006	24,792
Operating expenses:
Sales and marketing	23,188	18,227
Loss before income taxes	(11,729)	(11,518)
Income tax expense	(139)	(83)
Net loss	$ (11,868)	$ (11,601)
Net loss per common share, basic and diluted	$ (0.37)	$ (0.40)
Adoption of New Standard
Revenue:
Subscription and support		$ 31,554
Professional services and other		2,918
Total revenue		34,472
Cost of revenue:
Professional services and other		2,575
Gross profit		24,792
Operating expenses:
Sales and marketing		18,227
Loss before income taxes		(11,518)
Income tax expense		(83)
Net loss		$ (11,601)
Net loss per common share, basic and diluted		$ (0.40)
Adoption of New Standard | As Previously Reported
Revenue:
Subscription and support		$ 30,513
Professional services and other		3,466
Total revenue		33,979
Cost of revenue:
Professional services and other		2,511
Gross profit		24,363
Operating expenses:
Sales and marketing		18,986
Loss before income taxes		(12,700)
Income tax expense		(31)
Net loss		$ (12,731)
Net loss per common share, basic and diluted		$ (0.44)
Adoption of New Standard | Adjustments
Revenue:
Subscription and support		$ 1,041
Professional services and other		(548)
Total revenue		493
Cost of revenue:
Professional services and other		64
Gross profit		429
Operating expenses:
Sales and marketing		(759)
Loss before income taxes		1,182
Income tax expense		(52)
Net loss		$ 1,130
Net loss per common share, basic and diluted		$ 0.04