Other	9 Months Ended
Sep. 30, 2020
Debt and Other Disclosures [Abstract]
Debt	Debt In September 2020, our $400.0 million 5.625% senior unsecured notes matured. During the nine months ended September 30, 2020, we made principal payments of $45.0 million on our senior secured non-recourse notes issued by Northwind Holdings, LLC (Northwind Holdings). In October 2020, Northwind Holdings formally submitted its intention to redeem the remaining $35.0 million of principal on its senior secured non-recourse notes in December 2020. Funds for the redemption are held in the debt service coverage account of Northwind Holdings. In May 2020, we issued $500.0 million of 4.500% senior notes due 2025. The notes are callable at or above par and rank equally in the right of payment with all of our other unsecured and unsubordinated debt. In September 2019, pursuant to a cash tender offer, we purchased and retired (i) $20.2 million aggregate liquidation amount of our 7.405% capital securities due 2038 issued by Provident Financing Trust I (the Trust), which resulted in the reduction of a corresponding principal amount of our 7.405% junior subordinated debt securities due 2038 issued by Unum Group to the Trust; (ii) $30.3 million aggregate principal amount of our 7.190% medium-term notes due 2028; (iii) $30.0 million aggregate principal amount of our 7.250% senior notes due 2028; and (iv) $256.0 million aggregate principal amount of our 3.000% senior notes due 2021. In connection with the tender offer, we incurred costs of $25.2 million related to the early retirement of debt. At September 30, 2020, letters of credit totaling $0.6 million had been issued from our credit facilities, but there were no borrowed amounts outstanding. Borrowings under the credit facilities are for general corporate uses and are subject to financial covenants, negative covenants, and events of default that are customary. The two primary financial covenants include limitations based on our leverage ratio and consolidated net worth. We are also subject to covenants that limit subsidiary indebtedness. The credit facilities provide for borrowings at an interest rate based either on the prime rate or LIBOR.
Organizational Design Update	Costs Related to Organizational Design UpdateDuring the third quarter of 2020, we realigned certain parts of our organizational structure by shifting resources to accelerate growth, fund priority investments, and simplify and improve our business practices. In connection with this update, we incurred charges of $23.3 million, which primarily consisted of employee severance and benefit costs as well as certain costs related to lease terminations and the disposal of certain fixed assets. These costs were recorded within either compensation expense or other expenses in the consolidated statements of income and were included within our Corporate segment. This update did not result in the exit or disposal of any of our lines of business and we do not expect material additional costs associated with this update in the future.
Statutory Financial Information	Regulatory ExaminationIn connection with a financial examination of Unum Life Insurance Company of America (Unum America), which closed at the end of the second quarter of 2020, the Maine Bureau of Insurance (MBOI) concluded that Unum America’s long-term care statutory reserves are deficient by $2.1 billion as of December 31, 2018, the financial statement date of the examination period. The MBOI granted permission to Unum America on May 1, 2020, to phase in the additional statutory reserves over seven years beginning with year-end 2020 and ending with year-end 2026. The 2020 phase-in amount is estimated to be between $200 million and $250 million. This strengthening will be accomplished by our actuaries incorporating explicitly agreed upon margins into our existing assumptions for annual statutory reserve adequacy testing. These actions will add margin to Unum America's best estimate assumptions. Our long-term care reserves and financial results reported under generally accepted accounting principles are not affected by the MBOI’s examination conclusion. We plan to fund the additional statutory reserves with expected cash flows. If the permitted practice was not granted by the MBOI to phase in these additional statutory reserves, the impact to the risk-based capital ratio would have triggered a regulatory event.
Lessee, Operating Leases	Impairment Loss on ROU AssetDuring the second quarter of 2020, we recognized an impairment loss of $12.7 million on the ROU asset related to one of our operating leases for office space that we do not plan to continue using to support our general operations. The impairment loss was recorded as a result of a decrease in the fair value of the ROU asset compared to its carrying value. The fair value of the ROU asset was determined based on a discounted cash flow model utilizing estimated market rates for sub-lease rentals. The impairment loss is recorded within other expenses in the consolidated statements of income and is included within our Corporate segment.
Income Tax Disclosure	Income Tax On July 22, 2020, the Finance Bill 2019-21 was enacted, resulting in a U.K. tax rate increase from 17 percent to 19 percent, retroactively effective April 1, 2020, which resulted in $9.3 million of additional tax expense through continuing operations for the revaluation of our tax assets and liabilities in the third quarter of 2020.

Other

9 Months Ended

Sep. 30, 2020

Debt and Other Disclosures [Abstract]

In September 2020, our $400.0 million 5.625% senior unsecured notes matured.

During the nine months ended September 30, 2020, we made principal payments of $45.0 million on our senior secured non-recourse notes issued by Northwind Holdings, LLC (Northwind Holdings). In October 2020, Northwind Holdings formally submitted its intention to redeem the remaining $35.0 million of principal on its senior secured non-recourse notes in December 2020. Funds for the redemption are held in the debt service coverage account of Northwind Holdings.

In May 2020, we issued $500.0 million of 4.500% senior notes due 2025. The notes are callable at or above par and rank equally in the right of payment with all of our other unsecured and unsubordinated debt.

In September 2019, pursuant to a cash tender offer, we purchased and retired (i) $20.2 million aggregate liquidation amount of our 7.405% capital securities due 2038 issued by Provident Financing Trust I (the Trust), which resulted in the reduction of a corresponding principal amount of our 7.405% junior subordinated debt securities due 2038 issued by Unum Group to the Trust; (ii) $30.3 million aggregate principal amount of our 7.190% medium-term notes due 2028; (iii) $30.0 million aggregate principal amount of our 7.250% senior notes due 2028; and (iv) $256.0 million aggregate principal amount of our 3.000% senior notes due 2021. In connection with the tender offer, we incurred costs of $25.2 million related to the early retirement of debt.

At September 30, 2020, letters of credit totaling $0.6 million had been issued from our credit facilities, but there were no borrowed amounts outstanding. Borrowings under the credit facilities are for general corporate uses and are subject to financial covenants, negative covenants, and events of default that are customary. The two primary financial covenants include limitations based on our leverage ratio and consolidated net worth. We are also subject to covenants that limit subsidiary indebtedness. The credit facilities provide for borrowings at an interest rate based either on the prime rate or LIBOR.

Organizational Design Update

Costs Related to Organizational Design UpdateDuring the third quarter of 2020, we realigned certain parts of our organizational structure by shifting resources to accelerate growth, fund priority investments, and simplify and improve our business practices. In connection with this update, we incurred charges of $23.3 million, which primarily consisted of employee severance and benefit costs as well as certain costs related to lease terminations and the disposal of certain fixed assets. These costs were recorded within either compensation expense or other expenses in the consolidated statements of income and were included within our Corporate segment. This update did not result in the exit or disposal of any of our lines of business and we do not expect material additional costs associated with this update in the future.

Statutory Financial Information

Regulatory ExaminationIn connection with a financial examination of Unum Life Insurance Company of America (Unum America), which closed at the end of the second quarter of 2020, the Maine Bureau of Insurance (MBOI) concluded that Unum America’s long-term care statutory reserves are deficient by $2.1 billion as of December 31, 2018, the financial statement date of the examination period. The MBOI granted permission to Unum America on May 1, 2020, to phase in the additional statutory reserves over seven years beginning with year-end 2020 and ending with year-end 2026. The 2020 phase-in amount is estimated to be between $200 million and $250 million. This strengthening will be accomplished by our actuaries incorporating explicitly agreed upon margins into our existing assumptions for annual statutory reserve adequacy testing. These actions will add margin to Unum America's best estimate assumptions. Our long-term care reserves and financial results reported under generally accepted accounting principles are not affected by the MBOI’s examination conclusion. We plan to fund the additional statutory reserves with expected cash flows. If the permitted practice was not granted by the MBOI to phase in these additional statutory reserves, the impact to the risk-based capital ratio would have triggered a regulatory event.

Lessee, Operating Leases

Impairment Loss on ROU AssetDuring the second quarter of 2020, we recognized an impairment loss of $12.7 million on the ROU asset related to one of our operating leases for office space that we do not plan to continue using to support our general operations. The impairment loss was recorded as a result of a decrease in the fair value of the ROU asset compared to its carrying value. The fair value of the ROU asset was determined based on a discounted cash flow model utilizing estimated market rates for sub-lease rentals. The impairment loss is recorded within other expenses in the consolidated statements of income and is included within our Corporate segment.

Income Tax Disclosure

Income Tax

On July 22, 2020, the Finance Bill 2019-21 was enacted, resulting in a U.K. tax rate increase from 17 percent to 19 percent, retroactively effective April 1, 2020, which resulted in $9.3 million of additional tax expense through continuing operations for the revaluation of our tax assets and liabilities in the third quarter of 2020.