Accumulated Other Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2022

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Components of Accumulated Other Comprehensive Income, Net of Tax

The following tables summarize those reclassification adjustments (net of taxes) for the periods indicated: 

	Year Ended December 31, 2022
	Foreign currency translation adjustment		Net unrealized gains (losses) on securities		Net unrealized gains on derivative transactions		Unamortized net (losses) on Pension Plans		Accumulated other comprehensive (loss) income
Balance at December 31, 2021	$	(326.9)	$	256.6	$	12.4	$	(92.1)	$	(150.0)
Change in accumulated other comprehensive income (loss) before reclassifications	(67.1)		(808.7)		—		9.0		(866.8)
Amounts reclassified from accumulated other comprehensive income (loss)	—		38.9		(2.6)		(5.7)		30.6
Net current-period other comprehensive income (loss)	(67.1)		(769.8)		(2.6)		3.3		(836.2)
Balance at December 31, 2022	$	(394.0)	$	(513.2)	$	9.8	$	(88.8)	$	(986.2)

	Year Ended December 31, 2021
	Foreign currency translation adjustment		Net unrealized gains on securities		Net unrealized gains on derivative transactions		Unamortized net (losses) on Pension Plans		Accumulated other comprehensive income (loss)
Balance at December 31, 2020	$	(295.6)	$	1,097.6	$	14.7	$	(106.9)	$	709.8
Change in accumulated other comprehensive income (loss) before reclassifications	(31.0)		(215.9)		—		17.3		(229.6)
Amounts reclassified from accumulated other comprehensive income (loss)	(0.3)		(625.1)		(2.3)		(2.5)		(630.2)
Net current-period other comprehensive income (loss)	(31.3)		(841.0)		(2.3)		14.8		(859.8)
Balance at December 31, 2021	$	(326.9)	$	256.6	$	12.4	$	(92.1)	$	(150.0)

	Year Ended December 31, 2020
	Foreign currency translation adjustment		Net unrealized gains on securities		Net unrealized gains on derivative transactions		Unamortized net (losses) on Pension Plans		Accumulated other comprehensive income
Balance at December 31, 2019	$	(358.9)	$	872.0	$	17.1	$	(118.7)	$	411.5
Change in accumulated other comprehensive income (loss) before reclassifications	24.9		233.5		—		15.8		274.2
Amounts reclassified from accumulated other comprehensive income (loss)	38.4		(7.9)		(2.4)		(4.0)		24.1
Net current-period other comprehensive income (loss)	63.3		225.6		(2.4)		11.8		298.3
Balance at December 31, 2020	$	(295.6)	$	1,097.6	$	14.7	$	(106.9)	$	709.8

Reclassification out of Accumulated Other Comprehensive Income

The following tables summarize the reclassifications out of AOCI for the periods indicated.

Details about AOCI components	Amount reclassified from AOCI						Affected line item in the statement where net income is presented
	Years Ended December 31,
	2022		2021		2020
Foreign currency translation adjustment	$	—	$	(0.8)	$	38.4	Underwriting, selling, general and administrative expenses (see Note 4)
	—		0.5		—		Provision for income taxes
	$	—	$	(0.3)	$	38.4	Net of tax
Net unrealized gains (losses) on securities	$	49.2	$	(797.8)	$	(10.0)	Net realized (losses) gains on investments and fair value changes to equity securities
	(10.3)		172.7		2.1		Provision for income taxes
	$	38.9	$	(625.1)	$	(7.9)	Net of tax
Unrealized gains on derivative transactions	$	(3.2)	$	(2.8)	$	(2.9)	Interest expense
	0.6		0.5		0.5		Provision for income taxes
	$	(2.6)	$	(2.3)	$	(2.4)	Net of tax
Amortization of pension and postretirement unrecognized net periodic benefit cost:
Amortization of net loss	$	4.4	$	7.2	$	5.1	(1)
Amortization of prior service credit	(13.5)		(13.5)		(11.3)		(1)
Settlement loss	1.9		3.1		1.0		(1)
	(7.2)		(3.2)		(5.2)		Total before tax
	1.5		0.7		1.2		Provision for income taxes
	$	(5.7)	$	(2.5)	$	(4.0)	Net of tax
Total reclassifications for the period	$	30.6	$	(630.2)	$	24.1	Net of tax

(1)These AOCI components are included in the computation of net periodic pension cost. See Note 24 for additional information.