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Investments in Symetra (Symetra) (Details) - USD ($) $ / shares in Units, $ in Millions |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
Feb. 01, 2016 | Sep. 30, 2017 | Sep. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Sep. 30, 2017 | Sep. 30, 2016 | Dec. 31, 2016
Investments in unconsolidated affiliates |  |  |  |  |  |  |  |  |
Unrealized gains (losses) on investments |  | $ 26.1 | $ 9.9 |  |  |  | $ 82.1 | $ (240.7) |
Trading securities unrealized holding gain on investment after tax |  | $ 22.8 | 10.0 |  |  |  | 76.2 | (199.6) |
Sales of common equity securities |  |  |  |  |  |  | $ 407.8 | 683.0 |
Common shares, par value per share (in dollars per share) |  | $ 1.00 |  |  |  |  | $ 1.00 |  | $ 1.00
Net realized and unrealized investment gains |  | $ 32.5 | $ 10.9 |  |  |  | $ 102.5 | $ 27.2 |
Symetra |  |  |  |  |  |  |  |  |
Investments in unconsolidated affiliates |  |  |  |  |  |  |  |  |
Unrealized gains (losses) on investments |  |  |  |  | $ 258.8 |  |  |  |
Trading securities unrealized holding gain on investment after tax |  |  |  |  | $ 241.1 |  |  |  |
Sales of common equity securities | $ 658.0 |  |  |  |  |  |  |  |
Common shares, par value per share (in dollars per share) | $ 32.00 |  |  |  |  |  |  |  |
Net realized and unrealized investment gains |  |  |  | $ 4.7 |  |  |  |  |
Symetra |  |  |  |  |  |  |  |  |
Investments in unconsolidated affiliates |  |  |  |  |  |  |  |  |
Common stock, dividends, per share, cash paid | $ 0.50 |  |  |  |  | $ 0.50 |  |  |
Sales of common equity securities | $ 658.0 |  |  |  |  |  |  |  |

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- Definition This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (c)-(e) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c),9(a)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27405-111563 + Details
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