Income Taxes- Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Deferred tax assets:
Research tax credits	$ 10,782	$ 9,876
Intangibles	6,738	5,995
Other	78	18
Net operating loss	160,319	144,866
Share-based compensation	10,738	10,249
Lease liability	206	0
Subtotal	188,861	171,004
Valuation allowance	(187,762)	(171,004)
Deferred tax liabilities:
Right of use	(334)	0
Other	(765)	0
Total net deferred tax assets	$ 0	$ 0