Leases - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) ft² renewal_option	Dec. 31, 2018 USD ($)	Dec. 31, 2015 ft² term	Dec. 31, 2011 ft² lease building	Dec. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 88,202				$ 325,564
Present value of lease liabilities	$ 95,796				360,984
Rental expense		$ 17,300
Corporate Headquarters
Lessee, Lease, Description [Line Items]
Number of leases | lease				2
Area of real estate property (in square feet) | ft²				1,100,000
Lease agreements number of buildings | building				2
Option to extend lease term				15 years
Optional term of lease agreement (in years)				10 years
San Diego Lease
Lessee, Lease, Description [Line Items]
Area of real estate property (in square feet) | ft²			170,000
Length of lease			16 years
Amount of optional renewal terms | term			2
Optional renewal term length			5 years
Cell and Genetic Therapies Lease
Lessee, Lease, Description [Line Items]
Area of real estate property (in square feet) | ft²	269,000
Optional term of lease agreement (in years)	10 years
Lease agreement initial term	15 years
Number of optional renewal terms | renewal_option	2
Operating lease assets					253,500
Present value of lease liabilities					$ 286,600
Buildings and improvements
Lessee, Lease, Description [Line Items]
Property and equipment useful life		40 years