Fair Value Measurements (Fair Value, Marketable Securities Measured on Recurring and Nonrecurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Cash and cash equivalents, fair value disclosure	$ 58,019	$ 84,709
Available-for-sale securities, fair value disclosure	346,757	334,980
Total financial assets	358,104	382,267
Level 1
Total financial assets	31,414	52,284
Level 2
Total financial assets	326,690	329,983
Level 3
Total financial assets	0	0
Money market funds
Cash and cash equivalents, fair value disclosure	11,347	39,287
Money market funds \| Level 1
Cash and cash equivalents, fair value disclosure	11,347	39,287
Money market funds \| Level 2
Cash and cash equivalents, fair value disclosure	0	0
Money market funds \| Level 3
Cash and cash equivalents, fair value disclosure	0	0
Commercial paper
Cash and cash equivalents, fair value disclosure		8,000
Commercial paper \| Level 1
Cash and cash equivalents, fair value disclosure		0
Commercial paper \| Level 2
Cash and cash equivalents, fair value disclosure		8,000
Commercial paper \| Level 3
Cash and cash equivalents, fair value disclosure		0
Corporate debt securities
Available-for-sale securities, fair value disclosure	179,636	232,492
Corporate debt securities \| Level 1
Available-for-sale securities, fair value disclosure	0	0
Corporate debt securities \| Level 2
Available-for-sale securities, fair value disclosure	179,636	232,492
Corporate debt securities \| Level 3
Available-for-sale securities, fair value disclosure	0	0
Municipal bonds
Available-for-sale securities, fair value disclosure		5,027
Municipal bonds \| Level 1
Available-for-sale securities, fair value disclosure		0
Municipal bonds \| Level 2
Available-for-sale securities, fair value disclosure		5,027
Municipal bonds \| Level 3
Available-for-sale securities, fair value disclosure		0
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Available-for-sale securities, fair value disclosure	143,612	84,464
Commercial Paper, Not Included with Cash and Cash Equivalents [Member] \| Level 1
Available-for-sale securities, fair value disclosure	0	0
Commercial Paper, Not Included with Cash and Cash Equivalents [Member] \| Level 2
Available-for-sale securities, fair value disclosure	143,612	84,464
Commercial Paper, Not Included with Cash and Cash Equivalents [Member] \| Level 3
Available-for-sale securities, fair value disclosure	0	0
U.S. government agency bonds
Available-for-sale securities, fair value disclosure	3,442
U.S. government agency bonds \| Level 1
Available-for-sale securities, fair value disclosure	0
U.S. government agency bonds \| Level 2
Available-for-sale securities, fair value disclosure	3,442
U.S. government agency bonds \| Level 3
Available-for-sale securities, fair value disclosure	0
U.S Treasury securities
Available-for-sale securities, fair value disclosure	20,067	12,997
U.S Treasury securities \| Level 1
Available-for-sale securities, fair value disclosure	20,067	12,997
U.S Treasury securities \| Level 2
Available-for-sale securities, fair value disclosure	0	0
U.S Treasury securities \| Level 3
Available-for-sale securities, fair value disclosure	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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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.

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- Definition

Amount excluding accrued interest, 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/2009/role/commonPracticeRef
-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

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