Investment Income and Gains and Losses (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Components of Net Investment Income

The components of net investment income were as follows:

YEARS ENDED DECEMBER 31	2023			2022			2021
(in millions)
Fixed maturities	$	283.2		$	239.3		$	216.9
Limited partnerships		30.0			35.7			68.2
Mortgage loans		15.8			16.1			18.0
Equity securities		6.4			12.0			15.6
Other investments		10.6			4.6			3.0
Gross investment income		346.0			307.7			321.7
Less: investment expenses		(13.9	)		(11.4	)		(11.0	)
Net investment income	$	332.1		$	296.3		$	310.7

Schedule of Net Realized and Unrealized Gains (Losses) on Investments Including Impairments

Net realized and unrealized gains (losses) on investments, including impairments, were as follows:

YEARS ENDED DECEMBER 31	2023			2022			2021
(in millions)
Fixed maturities	$	(20.2	)	$	(45.2	)	$	1.7
Mortgage loans		(6.9	)		2.3			0.7
Equity securities		(5.6	)		(63.3	)		119.1
Other investments		0.2			(0.3	)		1.5
Net realized and unrealized investment gains (losses)	$	(32.5	)	$	(106.5	)	$	123.0

Schedule of Pre-tax Net Realized and Unrealized Gains (Losses) on Equity Securities

The following table provides pre-tax net realized and unrealized gains (losses) on equity securities:

YEARS ENDED DECEMBER 31	2023			2022			2021
(in millions)
Net gains (losses) recognized during the period	$	(5.6	)	$	(63.3	)	$	119.1
Less: net gains (losses) recognized on equity securities sold during the period		(11.6	)		(42.7	)		2.2
Net unrealized gains (losses) recognized during the period    on equity securities still held	$	6.0		$	(20.6	)	$	116.9

Schedule of Allowance for Credit Losses

The following table provides rollforwards of the allowance for credit losses on mortgage loans:

YEARS ENDED DECEMBER 31	2023			2022
(in millions)
Allowance for credit losses as of the beginning    of the period	$	3.2		$	7.1
Additional credit losses on investments for which an   allowance was previously recognized		6.9			0.2
Reductions for disposals		(0.1	)		(2.1	)
Recoveries		—			(2.0	)
Allowance for credit losses as of the end of the period	$	10.0		$	3.2

Schedule of Realized Gain (Loss)

The proceeds from sales of available-for-sale fixed maturities, and the gross realized gains and gross realized losses on those sales, were as follows:

YEARS ENDED DECEMBER 31	2023		2022		2021
(in millions)
Proceeds from sales	$	168.8	$	489.0	$	485.0
Gross gains		1.0		4.4		6.4
Gross losses		10.5		34.1		16.9