Fair Value of Financial Assets and Liabilities - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets:
Total, assets	$ 585,665	$ 585,828
Liabilities:
Total, liabilities	112,493	152,230
Fair Value, Inputs, Level 1
Assets:
Total, assets	0
Liabilities:
Total, liabilities	0
Fair Value, Inputs, Level 2
Assets:
Total, assets	585,665	585,828
Liabilities:
Total, liabilities	0
Fair Value, Inputs, Level 3
Assets:
Total, assets	0
Liabilities:
Total, liabilities	112,493	152,230
Money Market Funds
Assets:
Total, assets	167,938	273,827
Money Market Funds | Fair Value, Inputs, Level 1
Assets:
Total, assets	0
Money Market Funds | Fair Value, Inputs, Level 2
Assets:
Total, assets	167,938	273,827
Money Market Funds | Fair Value, Inputs, Level 3
Assets:
Total, assets	0
U.S. treasuries
Assets:
Total, assets	359,871	292,001
U.S. treasuries | Fair Value, Inputs, Level 1
Assets:
Total, assets	0	0
U.S. treasuries | Fair Value, Inputs, Level 2
Assets:
Total, assets	359,871	292,001
U.S. treasuries | Fair Value, Inputs, Level 3
Assets:
Total, assets	0
U.S. Government Agency Bonds
Assets:
Total, assets	57,856	20,000
U.S. Government Agency Bonds | Fair Value, Inputs, Level 1
Assets:
Total, assets	0
U.S. Government Agency Bonds | Fair Value, Inputs, Level 2
Assets:
Total, assets	57,856	20,000
U.S. Government Agency Bonds | Fair Value, Inputs, Level 3
Assets:
Total, assets	0
Contingent Consideration
Liabilities:
Total, liabilities	112,493	152,230
Contingent Consideration | Fair Value, Inputs, Level 1
Liabilities:
Total, liabilities	0
Contingent Consideration | Fair Value, Inputs, Level 2
Liabilities:
Total, liabilities	0
Contingent Consideration | Fair Value, Inputs, Level 3
Liabilities:
Total, liabilities	$ 112,493	$ 152,230