Investments in debt and equity securities - Gross Unrealized Gains and Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Gains	$ 2,007	$ 678
Losses	28,309	35,472
Municipal
Debt Securities, Available-for-sale [Line Items]
Gains	29	3
Losses	161	272
Corporate
Debt Securities, Available-for-sale [Line Items]
Gains	815	489
Losses	15,420	18,535
Foreign
Debt Securities, Available-for-sale [Line Items]
Gains	1,034	165
Losses	12,557	16,212
U.S. Treasury Bonds
Debt Securities, Available-for-sale [Line Items]
Gains	129	21
Losses	$ 171	$ 453

Amount, before tax, of unrealized gain 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).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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- Definition

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).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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