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Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
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Statement of Financial Position [Abstract] |  |
Amortized cost on fixed maturities trading investments | $ 3,011,979 | $ 2,969,541
Cost - equity security trading investments | 577,263 | 544,082
Cost - short-term investments | 367,837 | 254,518
Fixed assets, accumulated depreciation | $ 364,015 | $ 359,269
Common Stock |  |
Common stock, no par value (in dollars per share) | $ 0 | $ 0
Common stock, shares authorized (in shares) | 70,000,000 | 70,000,000
Common stock, shares issued (in shares) | 55,350,000 | 55,340,000
Common stock, shares outstanding (in shares) | 55,350,000 | 55,340,000

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