Investments in Equity Securities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Mar. 31, 2023	Sep. 30, 2022	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 1,279,955		$ 1,185,894
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cost	1,165,984		1,115,328
Gross Unrealized, Gains	229,473	$ 193,218
Gross Unrealized, Losses	(115,502)	(122,652)
Equity securities	1,279,955		1,185,894
Fair Value \| Common stock
Debt Securities, Available-for-sale [Line Items]
Cost	883,234		855,987
Gross Unrealized, Gains	227,947	192,165
Gross Unrealized, Losses	(53,582)	(65,401)
Equity securities	1,057,599		982,751
Fair Value \| Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Cost	282,750		259,341
Gross Unrealized, Gains	1,526	1,053
Gross Unrealized, Losses	(61,920)	$ (57,251)
Equity securities	222,356		203,143
Carrying Value
Debt Securities, Available-for-sale [Line Items]
Equity securities	1,279,955		1,185,894
Carrying Value \| Common stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	1,057,599		982,751
Carrying Value \| Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 222,356		$ 203,143

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740

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Amount of unrealized gain on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123583765&loc=SL75117546-209714

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