Length of Time Fixed Maturity Securities had been in a Gross Unrealized Loss Position (Detail) - USD ($)
$ in Millions

Sep. 30, 2025

Dec. 31, 2024

United States Government and Government Agencies and Authorities

Debt Securities, Available-for-sale, Unrealized Loss Position

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months

$ 22.4

$ 43.7

Gross Unrealized Loss, Less than 12 Months

0.3

4.1

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer

233.6

201.3

Gross Unrealized Loss, Greater than 12 Months

17.1

23.9

States, Municipalities, and Political Subdivisions

Debt Securities, Available-for-sale, Unrealized Loss Position

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months

168.2

425.8

Gross Unrealized Loss, Less than 12 Months

5.8

15.3

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer

1,902.4

1,926.2

Gross Unrealized Loss, Greater than 12 Months

474.4

554.4

Foreign Governments

Debt Securities, Available-for-sale, Unrealized Loss Position

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months

202.5

171.9

Gross Unrealized Loss, Less than 12 Months

7.9

10.6

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer

324.1

266.3

Gross Unrealized Loss, Greater than 12 Months

171.5

142.9

Public Utilities

Debt Securities, Available-for-sale, Unrealized Loss Position

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months

618.8

1,281.7

Gross Unrealized Loss, Less than 12 Months

20.0

48.4

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer

1,540.9

1,549.5

Gross Unrealized Loss, Greater than 12 Months

262.2

316.0

Mortgage/Asset-backed Securities

Debt Securities, Available-for-sale, Unrealized Loss Position

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months

^[1]

56.8

199.9

Gross Unrealized Loss, Less than 12 Months

^[1]

0.4

8.9

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer

^[1]

281.7

285.9

Gross Unrealized Loss, Greater than 12 Months

^[1]

16.9

28.3

All Other Corporate Bonds

Debt Securities, Available-for-sale, Unrealized Loss Position

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months

1,776.7

4,904.4

Gross Unrealized Loss, Less than 12 Months

47.9

182.5

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer

11,260.3

12,209.3

Gross Unrealized Loss, Greater than 12 Months

1,488.7

1,978.3

Redeemable Preferred Stocks

Debt Securities, Available-for-sale, Unrealized Loss Position

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months

0.0

3.9

Gross Unrealized Loss, Less than 12 Months

0.0

0.1

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer

3.7

Gross Unrealized Loss, Greater than 12 Months

0.2

0.3

Fixed Maturity Securities

Debt Securities, Available-for-sale, Unrealized Loss Position

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months

2,845.4

7,031.3

Gross Unrealized Loss, Less than 12 Months

82.3

269.9

Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer

15,546.7

16,442.2

Gross Unrealized Loss, Greater than 12 Months

$ 2,431.0

$ 3,044.1

[1]	1Includes credit-tranched securities collateralized by loan obligations, auto loans, and other asset types

Unum Group 10-Q