Common Stock and Stockholders' Equity - Employee Stock Purchase Plan (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Jul. 31, 2015	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Employee Stock Purchase Plan
Stock-based compensation		$ 18,315	$ 13,523
ESPP
Employee Stock Purchase Plan
Shares reserved for issuance under the plan (in shares)		832,492
Maximum offering period	27 months
Stock purchase price as a percentage of fair value (as a percent)	85.00%
Issuance of stock under employee stock purchase plan (in shares)				64,497
Remaining shares available for issuance under the plan (in shares)		555,267
Stock-based compensation		$ 400	$ 300
Unrecognized compensation cost		$ 200
Period over which unrecognized compensation cost is expected to be recognized		1 month 6 days