Realized Investment Gains and Losses Reported in Consolidated Statements of Income (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Fixed Maturity Securities
Gross Gains on Sales	$ 1.4	$ 3.3
Gross Losses on Sales	(0.7)	(7.9)
Debt Securities, Available-for-sale, Credit Loss	(53.9)	0.0
Mortgage Loans and Other Invested Assets
Gross Gains on Sales	0.3	0.9
Gross Losses on Sales	(0.2)	(0.1)
Credit Loss, Mortgage Loans	(2.6)
Gain (Loss) on Embedded Derivative	(86.9)	5.5
All Other Derivatives	(0.7)	0.3
Foreign Currency Transactions	(0.7)	(0.9)
Net Realized Investment Gain (Loss)	$ (144.0)	1.1
Commercial Real Estate and Unfunded Mortgage Loan Commitments
Mortgage Loans and Other Invested Assets
Credit Loss, Mortgage Loans		$ 0.0

This item represents the gross profit realized on the sale of investments not otherwise specified in the taxonomy

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Other Investments Gross Realized Losses

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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Amount of expense (reversal of expense) for expected credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), from change in present value of expected cash flows.

+ References

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Net Increase or Decrease in the fair value of the embedded derivative or group of embedded derivatives included in earnings in the period.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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Amount of realized and unrealized gain (loss) on investment.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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