Realized Investment Gains and Losses Reported in Consolidated Statements of Income (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Fixed Maturity Securities
Gross Gains on Sales	$ 3.3	$ 2.0
Gross Losses on Sales	(7.9)	(1.4)
Other-Than-Temporary Impairment Loss	0.0	(1.0)
Mortgage Loans and Other Invested Assets
Gross Gains on Sales	0.9	0.0
Gross Losses on Sales	(0.1)	0.0
Gain (Loss) on Embedded Derivative	5.5	(1.7)
Gain (Loss) on All Other Derivatives	0.3	0.7
Foreign Currency Transactions	(0.9)	(0.8)
Net Realized Investment Gain (Loss)	$ 1.1	$ (2.2)

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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No definition available.

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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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No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 15
-URI http://asc.fasb.org/subtopic&trid=2229187

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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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The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ References

No definition available.

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