Investments in Equity Securities (Investments in Equity Securities Available for Sale) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cost	$ 870,045	$ 516,014
Gross unrealized gains	100,275	124,323
Gross unrealized losses	(29,077)	(14,670)
Equity securities	941,243	625,667
Fair Value \| Common stocks
Debt Securities, Available-for-sale [Line Items]
Cost	619,896	335,617
Gross unrealized gains	92,401	28,742
Gross unrealized losses	(16,894)	(14,178)
Equity securities	695,403	350,181
Fair Value \| Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Cost	250,149	180,397
Gross unrealized gains	7,874	95,581
Gross unrealized losses	(12,183)	(492)
Equity securities	245,840	275,486
Carrying Value
Debt Securities, Available-for-sale [Line Items]
Equity securities	941,243	625,667
Carrying Value \| Common stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities	695,403	350,181
Carrying Value \| Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 245,840	$ 275,486

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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Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

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

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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