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Insurance Liabilities - Discounting Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Carrying amount of liabilities for unpaid claims	$ 1,172.1
Aggregate amount of discount	214.5
Long-Term Disability/Group Life Waiver
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Carrying amount of liabilities for unpaid claims	1,047.6	$ 1,029.9
Aggregate amount of discount	214.5	215.0
Interest accretion	$ 33.9	$ 34.2	$ 34.5
Long-Term Disability/Group Life Waiver | Minimum
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Discount rate	2.80%	3.30%
Long-Term Disability/Group Life Waiver | Maximum
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Discount rate	7.00%	7.00%
Dental/Vision/Short-Term Disability/Critical Illness/Accident
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Carrying amount of liabilities for unpaid claims	$ 70.4	$ 71.2
Group Life
Short-duration Insurance Contracts, Discounted Liabilities [Line Items]
Carrying amount of liabilities for unpaid claims	$ 54.1	$ 50.4

X

- Definition

The carrying amount as of the balance sheet date of loss reserves carried at present value.

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- Definition

Discount rate used to obtain present value of liability for unpaid claim and claim adjustment expense for short-duration contract issued by insurance entity.

+ References

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Amount of cumulative discount related to the time value of money deducted from short-duration insurance contract liabilities that are reported at present value.

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Amount of interest accretion recognized for short-duration insurance contract liabilities that are reported at present value.

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