Debt Additional Information

No definition available.

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Namespace Prefix:	unm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Facility, Additional Borrowing Capacity If Requested

+ References

No definition available.

+ Details

Name:	unm_LineOfCreditFacilityAdditionalBorrowingCapacityIfRequested
Namespace Prefix:	unm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
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Balance Type:
Period Type:

- Details

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Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Balance Type:
Period Type:

- Details

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Debt - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Aug. 02, 2022	Apr. 21, 2022
Notes 4.500 Due 2025
Debt Additional Information
Debt Instrument, Repurchased Face Amount	$ 500.0
Cost Related to Early Retirement of Debt	67.3
Senior Notes \| 4.125% Senior Notes due 2051
Debt Additional Information
Debt Instrument, Face Amount	600.0
Five-year Unsecured Revolving Credit Facility [Member]
Debt Additional Information
Line of Credit Facility, Maximum Borrowing Capacity			$ 500.0
Line of Credit Facility, Additional Borrowing Capacity If Requested			$ 200.0
Amount Outstanding on Line of Credit	0.0
Letters of Credit Outstanding, Amount	$ 0.4
Subsequent Event \| Five-Year $350 million Term Loan Facility
Debt Additional Information
Line of Credit Facility, Maximum Borrowing Capacity		$ 350.0