CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (shares) at Mar. 31, 2018		92,847,354
Beginning balance at Mar. 31, 2018	$ 218,774	$ 93	$ 425,790	$ (5,645)	$ (201,464)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under stock plans, less withholding (shares)		403,377
Issuance of common stock under stock plans, less withholding	777	$ 0	777
Stock-based compensation expense	9,304		9,304
Unrealized investment gain (loss)	113			113
Foreign currency translation adjustment	(1,672)			(1,672)
Net loss	(15,355)				(15,355)
Ending balance (shares) at Jun. 30, 2018		93,250,731
Ending balance at Jun. 30, 2018	251,842	$ 93	435,871	(7,204)	(176,918)
Beginning balance (shares) at Mar. 31, 2019		96,119,888
Beginning balance at Mar. 31, 2019	249,390	$ 96	506,949	(7,353)	(250,302)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under stock plans, less withholding (shares)		451,308
Issuance of common stock under stock plans, less withholding	1,494	$ 1	1,493
Stock-based compensation expense	14,059		14,059
Unrealized investment gain (loss)	121			121
Foreign currency translation adjustment	(652)			(652)
Net loss	(34,265)				(34,265)
Ending balance (shares) at Jun. 30, 2019		96,571,196
Ending balance at Jun. 30, 2019	$ 230,147	$ 97	$ 522,501	$ (7,884)	$ (284,567)