Income Taxes - Loss Before Income Taxes and Related Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
(Loss) income before income taxes:
Bermuda	$ (12,310)	$ (19,054)	$ (14,357)
Loss before income taxes	(254,798)	(288,228)	(273,075)
Current taxes:
Bermuda	1	0	0
Total current tax expense	336	761	476
Deferred taxes:
Bermuda	0	0	0
Total deferred tax expense	0	0	0
Total income tax expense	336	761	476
United States
(Loss) income before income taxes:
Foreign	(40,663)	(29,509)	(11,246)
Current taxes:
Foreign	335	758	473
Deferred taxes:
Foreign	0	0	0
Switzerland
(Loss) income before income taxes:
Foreign	(201,673)	(239,666)	(247,445)
Current taxes:
Foreign	0	0	0
Deferred taxes:
Foreign	0	0	0
Other
(Loss) income before income taxes:
Foreign	(152)	1	(27)
Current taxes:
Foreign	0	3	3
Deferred taxes:
Foreign	$ 0	$ 0	$ 0