Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (127,904)	$ (53,225)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	8,969	4,950
Depreciation	191	104
Amortization of debt discount and issuance costs	936	0
Foreign currency translation adjustment	353	148
Other	212	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(3,240)	(517)
Deferred tax assets	0	208
Income tax receivable	233	0
Other assets	(96)	(2,098)
Accounts payable	3,781	(1,975)
Income tax payable	0	561
Interest payable	18	0
Accrued expenses	8,176	2,569
Due to RSL, RSI and RSG	(1,382)	(2,299)
Deferred rent	567	213
Deferred interest payable	305	0
Net cash used in operating activities	(108,881)	(51,361)
Cash flows from investing activities:
Purchase of furniture and equipment	(390)	(157)
Net cash used in investing activities	(390)	(157)
Cash flows from financing activities:
Cash proceeds from stock option exercises	466	12
Net cash provided by financing activities	154,964	12
Net change in cash	45,693	(51,506)
Cash—beginning of period	108,624	180,838
Cash—end of period	154,317	129,332
Non-cash financing activities:
Offering costs, unpaid included in accrued expenses	292	0
Stock options exercised receivables, included in prepaid expenses and other current assets	(70)	0
Public Offering
Cash flows from financing activities:
Cash proceeds from issuance of common shares	74,683	0
Private Placement | Cowen and Company, LLC
Cash flows from financing activities:
Cash proceeds from issuance of common shares	57,315	0
Private Placement | Roivant Sciences, Ltd.
Cash flows from financing activities:
Cash proceeds from issuance of common shares	$ 22,500	$ 0