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Investments in Unconsolidated Affiliates (Symetra) (Details) - USD ($) |  | 3 Months Ended
--- | --- | ---
Feb. 01, 2016 | Mar. 31, 2016 | Dec. 31, 2015 | Mar. 31, 2015
Investments in unconsolidated affiliates |  |  |  |
Equity in earnings of unconsolidated affiliates, net of tax |  | $ 0 |  | $ 7,300,000
Unrealized gains (losses) on investments |  | (230,100,000) |  | 15,200,000
Revenues |  | 427,100,000 |  | 391,800,000
Total expenses |  | 415,600,000 |  | 391,300,000
Pre-tax (loss) income |  | 11,500,000 |  | 500,000
Net income |  | 19,300,000 |  | 77,000,000
Trading Securities Unrealized Holding Gain (Loss) on Investments after Tax |  | (195,700,000) |  | 12,600,000
Sales of common equity securities |  | $ 767,500,000 |  | 59,900,000
Common shares, par value per share (in dollars per share) |  | $ 1.00 | $ 1.00 |
Net realized and unrealized investment gains |  | $ 29,500,000 |  | $ 25,000,000
Symetra |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Unrealized gains (losses) on investments |  |  | $ 258,800,000 |
Term of amortization (in years) |  |  |  | 30 years
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity |  |  |  | $ 165,700,000
Trading Securities Unrealized Holding Gain (Loss) on Investments after Tax |  |  | $ 241,100,000 |
Sales of common equity securities | $ 658,000,000 |  |  |
Common shares, par value per share (in dollars per share) | $ 32.00 |  |  |
Net realized and unrealized investment gains |  | $ 4,700,000.00 |  |
Common Stock | Symetra |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Equity in earnings of unconsolidated affiliates, net of tax |  |  |  | 7,200,000
Proceeds from Equity Method Investment, Dividends or Distributions |  |  |  | 2,200,000
equity in earnings of unconsolidated affiliates | Symetra |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
After tax amortization through equity in earnings |  |  |  | 700,000
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity |  |  |  | 35,100,000
Net unrealized gains (losses) of unconsolidated affiliates | Symetra |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
After tax amortization through equity in net unrealized losses |  |  |  | 2,800,000
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity |  |  |  | 130,600,000
Expected [Member] | Symetra |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Dividends Payable, Amount Per Share |  | $ 32.00 |  |
Amortization of common share basis difference | Common Stock | Symetra |  |  |  |
Investments in unconsolidated affiliates |  |  |  |
Equity in earnings of unconsolidated affiliates, net of tax |  | $ 2,015 |  | $ 700,000

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