Leases (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Summary of Lease Assets and Liabilities

The following table summarizes the lease assets and liabilities as of December 31, 2023 and 2022 (in thousands):

	As of December 31,
	2023		2022
Assets
Operating lease assets	$	153,993	$	156,921
Total lease assets		153,993		156,921
Liabilities
Current
Operating lease liabilities		15,625		15,842
Non-current
Operating lease liabilities, net of current portion		223,007		228,179
Total lease liabilities	$	238,632	$	244,021

Summary of Operating Lease Costs Included in Research and Development and General and Administrative Expense, as well as Sublease Income

The following table summarizes operating lease costs included in research and development and general and administrative expense, as well as sublease income for the years ended December 31, 2023, 2022 and 2021 (in thousands):

	Years Ended December 31,
	2023			2022		2021
Operating lease costs	$	25,870		$	34,896	$	22,520
Short-term lease costs		—			824		11,087
Variable lease costs		14,387			11,882		8,402
Sublease income		(137	)		—		(5,253	)
Net lease cost	$	40,120		$	47,602	$	36,756

Summary of Maturity of Undiscounted Payments Due under Lease Liabilities and Present Value of Those Liabilities

The following table summarizes the maturity of undiscounted payments due under lease liabilities and the present value of those liabilities as of December 31, 2023 (in thousands):

	Total
2024		28,703
2025		28,825
2026		29,402
2027		28,669
2028		28,146
Thereafter		178,884
Total	$	322,629
Present value adjustment		(83,997	)
Present value of lease liabilities	$	238,632

Summary of Lease Term and Discount Rate

The following table summarizes the lease term (in years) and discount rate for operating leases as of December 31, 2023 and 2022:

	As of December 31,
	2023			2022
Weighted-average remaining lease term		10.8			11.8
Weighted-average discount rate		5.9	%		5.9	%

Lessee, Operating Lease Cash Flow Payments

The following table summarizes the cash paid for amounts included in the measurement of lease liabilities for the years ended December 31, 2023, 2022 and 2021 (in thousands):

	Years Ended December 31,
	2023			2022			2021
Cash paid for amounts included in measurement of lease liabilities:
Operating cash flows used in operating leases	$	(27,310	)	$	(17,004	)	$	(19,753	)
Operating lease non-cash items:
Right-of-use assets increased (decreased) through lease modifications and reassessments		2,660			1,208			(14,230	)
Right-of-use assets obtained in exchange for operating lease liabilities		7,552			—			152,486
Leasehold improvements paid directly by landlord		—			19,252			30,500