Income Taxes - Additional Information (Detail) - USD ($)		12 Months Ended
	Aug. 16, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Line Items]
Current tax expense		$ 0
Research and development expense		326,163,000	$ 283,166,000	$ 292,714,000
Deferred tax expense		0
Inflation reduction of corporate alternative minimum tax	15.00%
Inflation reduction of excise tax on stock repurchases	1.00%
Federal operating loss carryforwards		$ 1,500,000,000
Federal net operating loss carryforwards, limitation percentage		80.00%
Federal orphan drug tax credit carry forwards		$ 40,100,000
Tax credit carry forwards expiration period		2034
Change in amount of deferred tax assets		$ 122,700,000
Valuation allowance		593,286,000	470,604,000
Valuation allowance, increase (decrease), amount		122,700,000	94,500,000	(107,200,000)
Accrued interest or penalties related to uncertain tax positions		0	0
Uncertain tax positions		0	$ 0	$ 0
Begin to Expire 2033 [Member]
Income Tax Disclosure [Line Items]
Federal operating loss carryforwards		$ 30,200,000
Federal net operating loss carryforwards expiration year		2033
Begin to Expire 2028 [Member]
Income Tax Disclosure [Line Items]
State operating loss carryforwards		$ 669,500,000
State net operating loss carryforwards expiration year		2031
Domestic Tax Authority [Member]
Income Tax Disclosure [Line Items]
Research and development tax credits carryforwards		$ 68,400,000
Research and development tax credits carryforwards expiration year		2031
State and Local Jurisdiction [Member]
Income Tax Disclosure [Line Items]
Research and development tax credits carryforwards		$ 12,500,000
Research and development tax credits carryforwards expiration year		2027
Research and Development Expense [Member]
Income Tax Disclosure [Line Items]
TCJA, Capitalized amout		$ 319,000,000.0