Revenue, Credit Concentrations and Geographic Information - Disaggregates of Total Net Product Revenues Based on Patient Location (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Net product revenues	$ 429,485	$ 387,763	$ 931,554	$ 788,508
United States
Disaggregation of Revenue [Line Items]
Net product revenues	232,552	169,407	476,724	360,343
Europe
Disaggregation of Revenue [Line Items]
Net product revenues	109,259	119,561	254,295	244,100
Latin America
Disaggregation of Revenue [Line Items]
Net product revenues	37,864	46,494	97,788	80,333
Rest of world
Disaggregation of Revenue [Line Items]
Net product revenues	49,810	52,301	102,747	103,732
Total net product revenues
Disaggregation of Revenue [Line Items]
Net product revenues	419,032	379,075	908,075	773,558
Marketed by Company
Disaggregation of Revenue [Line Items]
Net product revenues	386,740	373,249	820,117	722,465
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim
Disaggregation of Revenue [Line Items]
Net product revenues	386,740	373,249	820,117	722,465
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | United States
Disaggregation of Revenue [Line Items]
Net product revenues	197,171	160,918	378,842	305,203
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Europe
Disaggregation of Revenue [Line Items]
Net product revenues	104,319	113,593	245,170	236,678
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Latin America
Disaggregation of Revenue [Line Items]
Net product revenues	37,864	46,493	97,788	80,333
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Rest of world
Disaggregation of Revenue [Line Items]
Net product revenues	47,386	52,245	98,317	100,251
Marketed by Company | Total net product revenues
Disaggregation of Revenue [Line Items]
Net product revenues	386,740	373,249	820,117	722,465
Marketed by Genzyme | Aldurazyme
Disaggregation of Revenue [Line Items]
Net product revenues	$ 32,292	$ 5,826	$ 87,958	$ 51,093