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Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands | Jun. 30, 2021 | Dec. 31, 2020
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Statement of Financial Position [Abstract] |  |
Fixed income securities, held-to-maturity, fair value | $ 27,882 | $ 18,001
Fixed Income Securities, Available-for-sale, Allowance for Credit Loss | (6,011) | (3,969)
Fixed income securities, available-for-sale, amortized cost | 6,311,749 | 6,073,517
Commercial mortgage loan, fair value | 73,559 | 47,289
Equity Securities, cost | 320,586 | 301,551
Property and equipment, accumulated depreciation and amortization | $ 251,533 | $ 240,150
Preferred Stock, Shares Outstanding | 8,000 | 8,000
Preferred Stock |  |
Preferred stock, Par or Stated Value (in dollars per share) | $ 0 | $ 0
Preferred stock, shares authorized | 5,000,000 | 5,000,000
Series B |  |
Preferred Stock, Liquidation Preference (in dollars per share) | $ 25,000 | $ 25,000
Preferred stock, shares issued | 8,000 | 8,000
Preferred Stock, Shares Outstanding | 8,000 | 8,000
Common Stock [Member] |  |
Common stock, Par or Stated Value (in dollars per share) | $ 2 | $ 2
Common stock, shares authorized | 360,000,000 | 360,000,000
Common stock, shares issued | 104,371,083 | 104,032,912
Treasury stock [Member] |  |
Treasury stock, shares | 44,264,847 | 44,127,109

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