Short-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 129,741	$ 29,528
Gross Unrealized gain (Loss)	(19)
Estimated Fair Value	129,722	29,528
Municipal bonds and notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,001	28,998
Gross Unrealized gain (Loss)	(1)
Estimated Fair Value	6,000	28,998
Zero coupon bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	123,210
Gross Unrealized gain (Loss)	(18)
Estimated Fair Value	123,192
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	530	530
Estimated Fair Value	$ 530	$ 530

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Publisher FASB
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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
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Amortized cost 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 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
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-Section 45
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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