Investments - Gains and Proceeds (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investments
Realized gain on sale of investments	$ 0	$ 0	$ 0	$ 0
Realized loss on sale of investments	0	$ 0	0	0
Proceeds from sale of available-for-sale debt securities	$ 0		0	13,000
Maturities of investments - debt securities			69,000	99,000
Purchases of available-for-sale securities			$ 37,400	$ 97,100

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

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Amount of realized loss 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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Amount of cash outflow for purchase of marketable security.

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Amount of cash inflow from maturity, prepayment and call 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
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-11

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
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-Name Accounting Standards Codification
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-Topic 230
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-Name Accounting Standards Codification
-Section 45
-Paragraph 12
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Amount of cash inflow from sale 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
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-11

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 9
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

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-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-11

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