Financial Instruments - Fair Value Measured On A Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	$ 46,242	$ 71,972
Long-term investments	50,256	125,320
Assets measured at fair value	443,704	554,322
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets measured at fair value	352,972	385,938
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets measured at fair value	78,552	159,763
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets measured at fair value	12,180	8,621
U.S. government treasury bonds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	9,078	22,251
Long-term investments	8,868	20,677
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	9,078	22,251
Long-term investments	8,868	20,677
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
Corporate bonds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		1,042
Short-term investments	29,454	35,065
Long-term investments	37,701	79,011
Corporate bonds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Long-term investments	0	0
Corporate bonds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		1,042
Short-term investments	29,454	35,065
Long-term investments	37,701	79,011
Corporate bonds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Long-term investments	0	0
Municipal bonds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		516
Short-term investments	4,015	3,657
Long-term investments	672	3,440
Municipal bonds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Long-term investments	0	0
Municipal bonds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		516
Short-term investments	4,015	3,657
Long-term investments	672	3,440
Municipal bonds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Long-term investments	0	0
U.S. government agency bonds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	1,139	1,200
U.S. government agency bonds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
U.S. government agency bonds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	1,139	1,200
U.S. government agency bonds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
Asset-backed securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	3,695	10,999
Long-term investments	1,876	20,992
Asset-backed securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
Asset-backed securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	3,695	10,999
Long-term investments	1,876	20,992
Asset-backed securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
Israeli funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Israeli funds		3,841
Israeli funds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Israeli funds		0
Israeli funds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Israeli funds		3,841
Israeli funds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Israeli funds		0
Investments in privately held companies | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in privately held companies	12,180	8,621
Investments in privately held companies | Fair Value, Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in privately held companies	0	0
Investments in privately held companies | Fair Value, Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in privately held companies	0	0
Investments in privately held companies | Fair Value, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in privately held companies	12,180	8,621
Money market funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	335,026	343,010
Money market funds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	335,026	343,010
Money market funds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
Money market funds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	$ 0	$ 0