Accumulated Other Comprehensive Income (Loss) ("AOCI") (Tables)

12 Months Ended

Dec. 31, 2023

Accumulated Other Comprehensive Income Other Comprehensive Income [Abstract]

Components of Accumulated Other Comprehensive Income (Loss)

The following table presents a summary of the changes in each component of AOCI for the years ended December 31, 2023, 2022 and 2021:

(in millions)	Unrealized gains (losses) on debt securities			Foreign currency translation adjustment			Pension benefit adjustment			Accumulated other comprehensive income (loss)
Balance at December 31, 2020	$	171.8		$	(38.0	)	$	(94.2	)	$	39.6
Change in unrealized gains (losses) on debt securities		(188.6	)		—			—			(188.6	)
Change in unrealized gains (losses) on debt securities      for which credit-related portion was recognized      in earnings		(0.4	)		—			—			(0.4	)
Change in foreign currency translation adjustment		—			(1.9	)		—			(1.9	)
Net actuarial gain		—			—			11.4			11.4
Amortization of net actuarial loss		—			—			6.8			6.8
Amortization of prior service credit		—			—			(1.3	)		(1.3	)
Tax effect		46.5			—			(4.5	)		42.0
Balance at December 31, 2021		29.3			(39.9	)		(81.8	)		(92.4	)
Change in unrealized gains (losses) on debt securities		(1,044.9	)		—			—			(1,044.9	)
Change in foreign currency translation adjustment		—			(43.3	)		—			(43.3	)
Net actuarial gain		—			—			57.4			57.4
Amortization of net actuarial loss		—			—			5.8			5.8
Amortization of prior service cost		—			—			0.2			0.2
Tax effect		264.0			1.1			(16.8	)		248.3
Balance at December 31, 2022		(751.6	)		(82.1	)		(35.2	)		(868.9	)
Change in unrealized gains (losses) on debt securities		262.3			—			—			262.3
Change in foreign currency translation adjustment		—			17.7			—			17.7
Net actuarial loss		—			—			(4.8	)		(4.8	)
Amortization of net actuarial loss		—			—			2.0			2.0
Tax effect		(64.3	)		(0.5	)		0.7			(64.1	)
Balance at December 31, 2023	$	(553.6	)	$	(64.9	)	$	(37.3	)	$	(655.8	)

Adjustments for Reclassification of Other Comprehensive Income (Loss)

The following table presents the other comprehensive income (loss) reclassification adjustments for the years ended December 31, 2023, 2022 and 2021:

	Unrealized gains (losses) on debt securities			Foreign currency translation adjustment			Pension benefit adjustment			Total other comprehensive income (loss)
	(in millions)
Year ended December 31, 2023
Pretax change before reclassifications	$	181.4		$	17.7		$	(4.8	)	$	194.3
Reclassifications out of AOCI		80.9			—			2.0			82.9
Tax effect		(64.3	)		(0.5	)		0.7			(64.1	)
Total other comprehensive income (loss), net of tax	$	198.0		$	17.2		$	(2.1	)	$	213.1
Year ended December 31, 2022
Pretax change before reclassifications	$	(1,181.4	)	$	(43.3	)	$	57.4		$	(1,167.3	)
Reclassifications out of AOCI		136.5			—			6.0			142.5
Tax effect		264.0			1.1			(16.8	)		248.3
Total other comprehensive income (loss), net of tax	$	(780.9	)	$	(42.2	)	$	46.6		$	(776.5	)
Year ended December 31, 2021
Pretax change before reclassifications	$	(168.8	)	$	(1.9	)	$	11.4		$	(159.3	)
Reclassifications out of AOCI		(20.2	)		—			5.5			(14.7	)
Tax effect		46.5			—			(4.5	)		42.0
Total other comprehensive income (loss), net of tax	$	(142.5	)	$	(1.9	)	$	12.4		$	(132.0	)

Reclassifications out of Accumulated Other Comprehensive Income (Loss)

The following table presents the effects of the reclassifications out of AOCI on the respective line items in the consolidated statements of income:

	Year ended December 31,
(in millions)	2023			2022			2021			Affected line items
Unrealized gains (losses) on debt      securities:
Net realized (losses) gains on sales of debt      securities	$	(80.9	)	$	(136.5	)	$	20.3		Net investment (losses) gains
Credit losses recognized on debt securities		—			—			(0.1	)	Net investment (losses) gains
Pretax total	$	(80.9	)	$	(136.5	)	$	20.2
Tax effect	$	19.8		$	36.2		$	(5.0	)
Pension benefit adjustment (1):
Amortization of net actuarial loss	$	(2.0	)	$	(5.8	)	$	(6.8	)	Other operating expenses
Amortization of prior service (cost) credit		—			(0.2	)		1.3		Other operating expenses
Pretax total	$	(2.0	)	$	(6.0	)	$	(5.5	)
Tax effect	$	0.5		$	1.6		$	1.5