Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (9,984)	$ (8,594)	$ (13,884)	$ (28,057)	$ (18,578)	$ (41,941)	$ (72,600)
Adjustments to reconcile net loss to net cash used in operating activities:
Unrealized foreign currency translation adjustment					392	(420)
Amortization of operating lease right-of-use assets					869	795
Stock-based compensation expense					2,698	3,026
Depreciation and non-cash amortization					672	734
Non-cash gain on long-term investment					(2,184)	0
Change in operating lease liabilities					(879)	(759)
Other					7	25
Changes in operating assets and liabilities:
Prepaid expenses and other current assets					(2,435)	1,356
Income tax receivable					(40)	(345)
Other non-current assets					(123)	341
Accounts payable					(2,240)	(131)
Accrued expenses					(3,482)	842
Net cash used in operating activities					(25,323)	(36,477)
Cash flows from investing activities:
Purchases of property and equipment					(130)	(174)
Net cash used in investing activities					(130)	(174)
Cash flows from financing activities:
Payments on long-term debt					(15,731)	(10,255)
Capital contribution received from Roivant Sciences, Inc.					75	76
Cash proceeds from stock option exercises					0	86
Cash proceeds from issuance of common stock, net of issuance costs					23,528	0
Net cash provided by (used in) financing activities					7,872	(10,093)
Net change in cash and cash equivalents					(17,581)	(46,744)
Cash and cash equivalents—beginning of period		$ 80,752		$ 106,999	80,752	106,999	106,999
Cash and cash equivalents—end of period	$ 63,171		$ 60,255		63,171	60,255	$ 80,752
Non-cash operating activities:
Operating lease right-of-use assets recognized upon and since the adoption of ASC 842, Leases, on April 1, 2019					0	2,986
Operating lease liabilities recognized upon and since the adoption of ASC 842, Leases, on April 1, 2019					0	2,400
Amounts reclassified from other non-current assets to operating lease right-of-use assets upon the adoption of ASC 842, Leases, on April 1, 2019					$ 0	$ 586