Financial Instruments - Fair Value Measured On A Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	$ 86,749	$ 71,972
Long-term investments	107,695	125,320
Assets measured at fair value	442,613	554,322
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets measured at fair value	283,071	385,938
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets measured at fair value	148,317	159,763
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets measured at fair value	11,225	8,621
Money market funds | Fair Value, Measurements, Recurring | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	236,944	343,010
Money market funds | Fair Value, Measurements, Recurring | Level 1 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	236,944	343,010
Money market funds | Fair Value, Measurements, Recurring | Level 2 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
Money market funds | Fair Value, Measurements, Recurring | Level 3 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	31,055	22,251
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	15,072	20,677
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 1 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	31,055	22,251
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 1 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	15,072	20,677
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 2 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 2 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 3 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
U.S. government treasury bonds | Fair Value, Measurements, Recurring | Level 3 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
Corporate bonds | Fair Value, Measurements, Recurring | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		1,042
Corporate bonds | Fair Value, Measurements, Recurring | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	41,164	35,065
Corporate bonds | Fair Value, Measurements, Recurring | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	72,757	79,011
Corporate bonds | Fair Value, Measurements, Recurring | Level 1 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Corporate bonds | Fair Value, Measurements, Recurring | Level 1 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Corporate bonds | Fair Value, Measurements, Recurring | Level 1 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
Corporate bonds | Fair Value, Measurements, Recurring | Level 2 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		1,042
Corporate bonds | Fair Value, Measurements, Recurring | Level 2 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	41,164	35,065
Corporate bonds | Fair Value, Measurements, Recurring | Level 2 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	72,757	79,011
Corporate bonds | Fair Value, Measurements, Recurring | Level 3 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Corporate bonds | Fair Value, Measurements, Recurring | Level 3 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Corporate bonds | Fair Value, Measurements, Recurring | Level 3 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
Municipal bonds | Fair Value, Measurements, Recurring | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		516
Municipal bonds | Fair Value, Measurements, Recurring | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	3,546	3,657
Municipal bonds | Fair Value, Measurements, Recurring | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	2,426	3,440
Municipal bonds | Fair Value, Measurements, Recurring | Level 1 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Municipal bonds | Fair Value, Measurements, Recurring | Level 1 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Municipal bonds | Fair Value, Measurements, Recurring | Level 1 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
Municipal bonds | Fair Value, Measurements, Recurring | Level 2 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		516
Municipal bonds | Fair Value, Measurements, Recurring | Level 2 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	3,546	3,657
Municipal bonds | Fair Value, Measurements, Recurring | Level 2 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	2,426	3,440
Municipal bonds | Fair Value, Measurements, Recurring | Level 3 | Cash equivalents:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents		0
Municipal bonds | Fair Value, Measurements, Recurring | Level 3 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Municipal bonds | Fair Value, Measurements, Recurring | Level 3 | Long-term investments:
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 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	1,168	1,200
U.S. government agency bonds | Fair Value, Measurements, Recurring | Level 1 | Long-term investments:
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 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	1,168	1,200
U.S. government agency bonds | Fair Value, Measurements, Recurring | Level 3 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
Asset-backed securities | Fair Value, Measurements, Recurring | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	10,984	10,999
Asset-backed securities | Fair Value, Measurements, Recurring | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	16,272	20,992
Asset-backed securities | Fair Value, Measurements, Recurring | Level 1 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Asset-backed securities | Fair Value, Measurements, Recurring | Level 1 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
Asset-backed securities | Fair Value, Measurements, Recurring | Level 2 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	10,984	10,999
Asset-backed securities | Fair Value, Measurements, Recurring | Level 2 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	16,272	20,992
Asset-backed securities | Fair Value, Measurements, Recurring | Level 3 | Short-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	0	0
Asset-backed securities | Fair Value, Measurements, Recurring | Level 3 | Long-term investments:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Long-term investments	0	0
Israeli funds | Fair Value, Measurements, Recurring | Prepaid expenses and other current assets:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Israeli funds		3,841
Israeli funds | Fair Value, Measurements, Recurring | Level 1 | Prepaid expenses and other current assets:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Israeli funds		0
Israeli funds | Fair Value, Measurements, Recurring | Level 2 | Prepaid expenses and other current assets:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Israeli funds		3,841
Israeli funds | Fair Value, Measurements, Recurring | Level 3 | Prepaid expenses and other current assets:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Israeli funds		0
Investments in privately held companies | Fair Value, Nonrecurring | Other assets:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in privately held companies	11,225	8,621
Investments in privately held companies | Fair Value, Nonrecurring | Level 1 | Other assets:
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 | Other assets:
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 | Other assets:
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in privately held companies	$ 11,225	$ 8,621