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Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Fixed-maturity securities held as available-for-sale, amortized cost | $ 4,197 | $ 4,438
Preferred stock, par value | $ 1 | $ 1
Preferred stock, authorized shares | 10,000,000 | 10,000,000
Preferred stock, issued | 0 | 0
Preferred stock, outstanding | 0 | 0
Common stock, par value | $ 1 | $ 1
Common stock, authorized shares | 400,000,000 | 400,000,000
Common stock, issued shares | 283,569,254 | 283,717,973
Accumulated other comprehensive income (loss), taxes | $ 7 | $ 16
Treasury stock, shares | 194,243,689 | 192,233,526
Non Variable Interest Entity [Member] |  |
Fixed-maturity securities held as available-for-sale, amortized cost | $ 3,812 | $ 3,728
Investments pledged as collateral, amortized cost | 34 | 147
Short-term investments held as available-for-sale, amortized cost | 448 | 589
Other investments, fair value | 0 | 4
Medium-term notes, financial instruments carried at fair value | 146 | 115
Variable Interest Entity Primary Beneficiary [Member] |  |
Investments held-to-maturity, fair value | 901 | 916
Variable interest entity notes, financial instruments carried at fair value | $ 1,031 | $ 1,069

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