Fair Value Measurements, Assets and Liabilities are Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands		Sep. 30, 2023	Mar. 31, 2023
Assets: [Abstract]
Investment		$ 250,393	$ 304,317
Earn-Out Shares [Member]
Recurring Fair Value Measurements [Abstract]
Non financial liabilities at fair value		27,600	15,200
Arbutus Biopharma Corporation [Member]
Assets: [Abstract]
Investment		78,900	117,700
Level 1 [Member] | Warrant [Member] | Public Warrants [Member]
Recurring Fair Value Measurements [Abstract]
Financial liabilities at fair value			29,900
Level 3 [Member] | Earn-Out Shares [Member]
Recurring Fair Value Measurements [Abstract]
Non financial liabilities at fair value		27,600	15,200
Level 3 [Member] | Warrant [Member] | Private Placement Warrants [Member]
Recurring Fair Value Measurements [Abstract]
Financial liabilities at fair value			15,200
Level 3 [Member] | Other Liability Instruments Measured At Fair Value Measurement [Member]
Recurring Fair Value Measurements [Abstract]
Other Liability instruments measured at fair value measurement		3,500	3,300
Recurring [Member]
Assets: [Abstract]
Total assets at fair value		1,245,423	1,801,043
Liabilities: [Abstract]
Debt issued by Dermavant to NovaQuest		217,031	207,640
Liability instruments measured at fair value	[1]	31,114	63,546
Total liabilities at fair value		248,145	271,186
Recurring [Member] | Money Market Funds [Member]
Assets: [Abstract]
Money market funds		995,030	1,496,726
Recurring [Member] | Common Shares [Member] | Datavant [Member]
Assets: [Abstract]
Investment		164,325	178,579
Recurring [Member] | Common Shares [Member] | Arbutus Biopharma Corporation [Member]
Assets: [Abstract]
Investment		78,860	117,708
Recurring [Member] | Other Investments [Member]
Assets: [Abstract]
Investment		7,208	8,030
Recurring [Member] | Level 1 [Member]
Assets: [Abstract]
Total assets at fair value		1,081,098	1,622,464
Liabilities: [Abstract]
Debt issued by Dermavant to NovaQuest		0	0
Liability instruments measured at fair value	[1]	0	29,895
Total liabilities at fair value		0	29,895
Recurring [Member] | Level 1 [Member] | Money Market Funds [Member]
Assets: [Abstract]
Money market funds		995,030	1,496,726
Recurring [Member] | Level 1 [Member] | Common Shares [Member] | Datavant [Member]
Assets: [Abstract]
Investment		0	0
Recurring [Member] | Level 1 [Member] | Common Shares [Member] | Arbutus Biopharma Corporation [Member]
Assets: [Abstract]
Investment		78,860	117,708
Recurring [Member] | Level 1 [Member] | Other Investments [Member]
Assets: [Abstract]
Investment		7,208	8,030
Recurring [Member] | Level 2 [Member]
Assets: [Abstract]
Total assets at fair value		0	0
Liabilities: [Abstract]
Debt issued by Dermavant to NovaQuest		0	0
Liability instruments measured at fair value	[1]	0	0
Total liabilities at fair value		0	0
Recurring [Member] | Level 2 [Member] | Money Market Funds [Member]
Assets: [Abstract]
Money market funds		0	0
Recurring [Member] | Level 2 [Member] | Common Shares [Member] | Datavant [Member]
Assets: [Abstract]
Investment		0	0
Recurring [Member] | Level 2 [Member] | Common Shares [Member] | Arbutus Biopharma Corporation [Member]
Assets: [Abstract]
Investment		0	0
Recurring [Member] | Level 2 [Member] | Other Investments [Member]
Assets: [Abstract]
Investment		0	0
Recurring [Member] | Level 3 [Member]
Assets: [Abstract]
Total assets at fair value		164,325	178,579
Liabilities: [Abstract]
Debt issued by Dermavant to NovaQuest		217,031	207,640
Liability instruments measured at fair value	[1]	31,114	33,651
Total liabilities at fair value		248,145	241,291
Recurring [Member] | Level 3 [Member] | Money Market Funds [Member]
Assets: [Abstract]
Money market funds		0	0
Recurring [Member] | Level 3 [Member] | Common Shares [Member] | Datavant [Member]
Assets: [Abstract]
Investment		164,325	178,579
Recurring [Member] | Level 3 [Member] | Common Shares [Member] | Arbutus Biopharma Corporation [Member]
Assets: [Abstract]
Investment		0	0
Recurring [Member] | Level 3 [Member] | Other Investments [Member]
Assets: [Abstract]
Investment		$ 0	$ 0

[1] At September 30, 2023,  Level 3 includes the fair value of the Earn-Out Shares of $27.6 million and other liability instruments issued of $3.5 million. At March 31, 2023, Level 1 includes the fair value of the Public Warrants of $29.9 million, and Level 3 includes the fair value of the Earn-Out Shares of $15.2 million, Private Placement Warrants of $15.2 million, and other liability instruments issued of $3.3 million.