Fair Value Measurements - Financial Assets and Liabilities Subject To Fair Value Measurements on a Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	$ 151,583	$ 37,803
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	90,169	37,803
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	61,414	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0	0
Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	62,082	36,801
Cash Equivalents [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	51,940	36,801
Cash Equivalents [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	6,000
Cash Equivalents [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	4,142
Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	51,940	36,801
Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	51,940	36,801
Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	10,142	0
Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0	0
Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	6,000
Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	4,142
Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0	0
Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0	0
Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Short-Term Marketable Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	89,501	1,002
Short-Term Marketable Securities [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	31,724
Short-Term Marketable Securities [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	17,435
Short-Term Marketable Securities [Member] | U.S. Treasuries [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	38,229	1,002
Short-Term Marketable Securities [Member] | U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	2,113
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	38,229	1,002
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasuries [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	38,229	1,002
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	51,272	0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	31,724
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	17,435
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasuries [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0	0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	2,113
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0	0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasuries [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	0	$ 0
Short-Term Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets fair value	$ 0