Revenue Recognition - Summary of Impact of ASC 606 (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018
Service revenue	$ 78,121
Product revenue	5,104
Total revenue	83,225	$ 69,098
Operating expenses:
Sales and marketing	53,305	41,110
Loss from operations	(15,983)	(5,457)
Net loss	$ (15,355)	(2,169)
Net loss per share:
Basic and diluted	$ (0.16)
Current assets:
Deferred sales commission costs	$ 12,706		$ 11,234
Other current assets	11,131		11,765
Non-current assets:
Deferred sales commission costs	27,041		26,942
Stockholders' equity:
Accumulated deficit	(176,918)		(161,563)
Cash Flow Line Items
Net loss	(15,355)	(2,169)
Deferred sales commission costs	(1,799)	0
Other current and noncurrent assets	(419)
Net cash provided by operating activities	789	$ 6,183
ASC 605 | Previous
Service revenue	78,242
Product revenue	5,011
Total revenue	83,253
Operating expenses:
Sales and marketing	55,104
Loss from operations	(17,754)
Net loss	$ (17,126)
Net loss per share:
Basic and diluted	$ (0.18)
Current assets:
Deferred sales commission costs			0
Other current assets			10,040
Non-current assets:
Deferred sales commission costs			0
Stockholders' equity:
Accumulated deficit			(201,464)
Cash Flow Line Items
Net loss	$ (17,126)
Deferred sales commission costs	0
Other current and noncurrent assets	(447)
Net cash provided by operating activities	789
ASC 606 | Adjustment
Service revenue	(121)
Product revenue	93
Total revenue	(28)
Operating expenses:
Sales and marketing	(1,799)
Loss from operations	1,771
Net loss	$ 1,771
Net loss per share:
Basic and diluted	$ 0.02
Current assets:
Deferred sales commission costs	$ 12,706		11,234
Other current assets	1,697		1,725
Non-current assets:
Deferred sales commission costs	27,041		26,942
Stockholders' equity:
Accumulated deficit	41,444		$ 39,901
Cash Flow Line Items
Net loss	1,771
Deferred sales commission costs	(1,799)
Other current and noncurrent assets	28
Net cash provided by operating activities	0
ASC 605 | Previous
Current assets:
Deferred sales commission costs	0
Other current assets	9,434
Non-current assets:
Deferred sales commission costs	0
Stockholders' equity:
Accumulated deficit	$ (218,362)