Commitments and Contingencies - Additional Information (Detail) € in Millions			1 Months Ended		3 Months Ended							12 Months Ended
	Dec. 15, 2021 USD ($) shares	Jun. 18, 2021 USD ($)	Apr. 30, 2020	May 31, 2017 USD ($)	Mar. 31, 2022 USD ($) $ / € $ / SFr	Mar. 31, 2022 EUR (€)	Mar. 31, 2022 CHF (SFr)	Dec. 31, 2021 USD ($) $ / SFr	Mar. 31, 2021 USD ($) $ / €	Mar. 31, 2020 USD ($)	Mar. 31, 2020 CHF (SFr)	Dec. 31, 2021 USD ($) $ / SFr	Dec. 31, 2021 CHF (SFr) $ / SFr	Mar. 31, 2022 CHF (SFr) $ / € $ / SFr
Loss Contingencies [Line Items]
Amount committed in investment					$ 42,600,000
Net cash distributions for investment					1,600,000
Other (Expense) Income, Net [Member]
Loss Contingencies [Line Items]
Investment income					4,000,000.0				$ 2,900,000
Other Assets [Member]
Loss Contingencies [Line Items]
Amount committed in investment					24,800,000
River Vision [Member]
Loss Contingencies [Line Items]
Maximum payment to be made upon attainment of milestones				$ 325,000,000.0
Maximum payment to be made upon attainment of milestones				325,000,000.0
River Vision [Member] | FDA Approval [Member]
Loss Contingencies [Line Items]
Maximum payment to be made upon attainment of milestones				100,000,000.0
Maximum payment to be made upon attainment of milestones				100,000,000.0
Alpine [Member]
Loss Contingencies [Line Items]
Upfront cash payments					25,000,000.0			$ 15,000,000.0
Maximum amount eligible to receive per program	$ 381,000,000.0
Total future success-based payments related to development, regulatory and commercial milestones	$ 1,520,000,000
Alpine [Member] | Private Placement [Member]
Loss Contingencies [Line Items]
Purchase of common stock shares | shares	951,980
AROXDH [Member]
Loss Contingencies [Line Items]
Upfront cash payment		$ 40,000,000.0
Maximum [Member] | AROXDH [Member]
Loss Contingencies [Line Items]
Maximum payment to be made upon attainment of milestones		$ 660,000,000.0
BUPHENYL, DUEXIS, PENNSAID 2%, PROCYSBI, QUINSAIR, RAVICTI, RAYOS, UPLIZNA and VIMOVO [Member]
Loss Contingencies [Line Items]
Purchase and other commitments outstanding purchase orders					24,300,000
Teprotumumab [Member] | River Vision [Member] | Net Sales Thresholds [Member]
Loss Contingencies [Line Items]
Maximum payment to be made upon attainment of milestones				225,000,000.0
Maximum payment to be made upon attainment of milestones				$ 225,000,000.0
AGC Biologics A/S [Member] | TEPEZZA [Member]
Loss Contingencies [Line Items]
Minimum binding purchase commitment					$ 106,200,000	€ 96.0
Currency exchange rate | $ / €					1.1059									1.1059
Catalent [Member] | TEPEZZA Drug Product [Member]
Loss Contingencies [Line Items]
Minimum binding purchase commitment					$ 6,500,000
Patheon Pharmaceuticals Inc. [Member] | TEPEZZA Drug Product [Member]
Loss Contingencies [Line Items]
Minimum binding purchase commitment					$ 7,800,000	€ 7.1
Currency exchange rate | $ / €					1.1059									1.1059
Bio-Technology General (Israel) Ltd [Member] | KRYSTEXXA Developed Technology [Member]
Loss Contingencies [Line Items]
Minimum binding purchase commitment					$ 32,000,000.0
Bio-Technology General (Israel) Ltd [Member] | KRYSTEXXA Developed Technology [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Purchase obligation percentage					80.00%	80.00%	80.00%
Boehringer Ingelheim [Member] | ACTIMMUNE Developed Technology [Member]
Loss Contingencies [Line Items]
Minimum binding purchase commitment					$ 10,300,000	€ 9.3
Currency exchange rate | $ / €									1.1059
S R One And Lundbeckfond [Member] | River Vision [Member]
Loss Contingencies [Line Items]
Percentage of net sales in earn-out payment				3.00%								0.893%	0.893%
Net sales minimum limit for royal payment				$ 300,000,000.0								$ 300,000,000.0
Percentage of right to receive payments			35.66%
Percentage of remaining net obligations payments			70.25%
Milestone incurred												$ 67,000,000.0
Roche [Member]
Loss Contingencies [Line Items]
Currency exchange rate | $ / SFr					1.0846									1.0846
Milestone incurred					$ 46,600,000		SFr 43,000,000.0
Roche [Member] | U.S. Food and Drug Administration (FDA) Approval [Member]
Loss Contingencies [Line Items]
Currency exchange rate | $ / SFr					1.0382									1.0382
Milestone incurred										$ 5,200,000	SFr 5,000,000.0
Roche [Member] | TEPEZZA [Member]
Loss Contingencies [Line Items]
Currency exchange rate | $ / SFr								1.1228				1.1228	1.1228
Milestone incurred												$ 56,100,000	SFr 50,000,000.0
Roche [Member] | River Vision [Member]
Loss Contingencies [Line Items]
Maximum payment to be made upon attainment of milestones | SFr														SFr 103,000,000.0
Maximum payment to be made upon attainment of milestones | SFr														SFr 103,000,000.0
Roche [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Percentage of net sales in earn-out payment					9.00%	9.00%	9.00%
Roche [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Percentage of net sales in earn-out payment					12.00%	12.00%	12.00%
TEPEZZA And KRYSTEXXA [Member]
Loss Contingencies [Line Items]
Advertising commitments					$ 23,900,000