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Fair Value Measurements - Assets Measured at Fair Value On a Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale	$ 935,844	$ 1,090,057
Cash equivalents
Cash Equivalents	147,463	268,349
Short-term
Debt Securities, Available-for-Sale	725,063	819,477
Long-term
Debt Securities, Available-for-Sale	63,318	2,231
Level 1
Debt Securities, Available-for-Sale	88,073	25,019
Level 1 | Cash equivalents
Cash Equivalents	88,073	25,019
Level 1 | Short-term
Debt Securities, Available-for-Sale	0	0
Level 1 | Long-term
Debt Securities, Available-for-Sale	0	0
Level 2
Debt Securities, Available-for-Sale	847,771	1,065,038
Level 2 | Cash equivalents
Cash Equivalents	59,390	243,330
Level 2 | Short-term
Debt Securities, Available-for-Sale	725,063	819,477
Level 2 | Long-term
Debt Securities, Available-for-Sale	63,318	2,231
Money market funds | Cash equivalents
Cash Equivalents	88,073	25,019
Money market funds | Level 1 | Cash equivalents
Cash Equivalents	88,073	25,019
Money market funds | Level 2 | Cash equivalents
Cash Equivalents	0	0
Commercial paper | Cash equivalents
Cash Equivalents	50,791	179,455
Commercial paper | Short-term
Debt Securities, Available-for-Sale	421,279	419,469
Commercial paper | Level 1 | Cash equivalents
Cash Equivalents	0	0
Commercial paper | Level 1 | Short-term
Debt Securities, Available-for-Sale	0	0
Commercial paper | Level 2 | Cash equivalents
Cash Equivalents	50,791	179,455
Commercial paper | Level 2 | Short-term
Debt Securities, Available-for-Sale	421,279	419,469
Federal agency debt securities | Short-term
Debt Securities, Available-for-Sale	107,222	0
Federal agency debt securities | Long-term
Debt Securities, Available-for-Sale	20,050	0
Federal agency debt securities | Level 1 | Short-term
Debt Securities, Available-for-Sale	0	0
Federal agency debt securities | Level 1 | Long-term
Debt Securities, Available-for-Sale	0	0
Federal agency debt securities | Level 2 | Short-term
Debt Securities, Available-for-Sale	107,222	0
Federal agency debt securities | Level 2 | Long-term
Debt Securities, Available-for-Sale	20,050	0
Municipal debt securities | Cash equivalents
Cash Equivalents	8,599	63,875
Municipal debt securities | Short-term
Debt Securities, Available-for-Sale	30,426	165,572
Municipal debt securities | Long-term
Debt Securities, Available-for-Sale	7,580	2,231
Municipal debt securities | Level 1 | Cash equivalents
Cash Equivalents	0	0
Municipal debt securities | Level 1 | Short-term
Debt Securities, Available-for-Sale	0	0
Municipal debt securities | Level 1 | Long-term
Debt Securities, Available-for-Sale	0	0
Municipal debt securities | Level 2 | Cash equivalents
Cash Equivalents	8,599	63,875
Municipal debt securities | Level 2 | Short-term
Debt Securities, Available-for-Sale	30,426	165,572
Municipal debt securities | Level 2 | Long-term
Debt Securities, Available-for-Sale	7,580	2,231
Corporate debt securities | Short-term
Debt Securities, Available-for-Sale	166,136	234,436
Corporate debt securities | Long-term
Debt Securities, Available-for-Sale	35,688	0
Corporate debt securities | Level 1 | Short-term
Debt Securities, Available-for-Sale	0	0
Corporate debt securities | Level 1 | Long-term
Debt Securities, Available-for-Sale	0	0
Corporate debt securities | Level 2 | Short-term
Debt Securities, Available-for-Sale	166,136	234,436
Corporate debt securities | Level 2 | Long-term
Debt Securities, Available-for-Sale	$ 35,688	$ 0

X

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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