Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands		6 Months Ended
		Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss		$ (99,922)	$ (138,472)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation		14,736	14,383
Depreciation and amortization	[1]	1,146	726
Amortization of debt discount and issuance costs		0	1,095
Foreign currency transaction gain		(10,287)	(584)
Other		393	215
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		2,657	225
Income tax receivable		0	507
Other assets		(648)	(799)
Accounts payable		(8,326)	(5,200)
Interest payable		0	(772)
Interest payable (related party)		(15)	0
Accrued expenses		11,081	(9,154)
Deferred revenue		(23,333)	0
Operating lease liabilities		(728)	(368)
Deferred interest payable		0	3,050
Amounts due to related parties		1,284	0
Other liabilities		1,386	0
Net cash used in operating activities		(110,576)	(135,148)
Cash flows from investing activities:
Purchases of marketable securities		(28,874)	(27,160)
Maturities of marketable securities		14,785	0
Purchases of property and equipment		(734)	(532)
Net cash used in investing activities		(14,823)	(27,692)
Cash flows from financing activities:
Proceeds from related party debt financing		140,000	0
Proceeds from stock option exercises		3,578	314
Net cash provided by financing activities		143,578	137,388
Net change in cash, cash equivalents and restricted cash		18,179	(25,452)
Cash, cash equivalents and restricted cash, beginning of period		78,018	157,199
Cash, cash equivalents and restricted cash, end of period		96,197	131,747
Non-cash financing activities:
Offering costs included in accounts payable and accrued expenses		0	70
Private Placement | Cowen and Company, LLC
Cash flows from financing activities:
Cash proceeds from issuance of common shares		0	2,546
Public Offering
Cash flows from financing activities:
Cash proceeds from issuance of common shares		$ 0	$ 134,528

[1] Includes amortization of operating lease right-of-use assets.