Other Comprehensive Income (Tables)

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Changes in Other Comprehensive Income

The following tables provide changes in other comprehensive income.

	Three Months Ended March 31,
	2018									2017
				Tax									Tax
				Benefit			Net of						Benefit			Net of
(in millions)	Pre-Tax			(Expense)			Tax			Pre-Tax			(Expense)			Tax
Unrealized gains (losses) on available-for-sale    securities:
Unrealized gains (losses) arising during period	$	(153.7	)	$	32.1		$	(121.6	)	$	38.0		$	(13.3	)	$	24.7
Amount of realized gains from sales and other		0.2			(2.5	)		(2.3	)		(4.1	)		(1.7	)		(5.8	)
Portion of other-than-temporary impairment    losses recognized in earnings		0.5			(0.1	)		0.4			0.2			(0.1	)		0.1
Adoption of Accounting Standards Update    2016-01 and 2018-02		(146.5	)		64.9			(81.6	)		—			—			—
Net unrealized gains (losses)		(299.5	)		94.4			(205.1	)		34.1			(15.1	)		19.0
Pension and postretirement benefits:
Net change in net actuarial loss and prior    service cost		(2.9	)		0.6			(2.3	)		3.5			(1.2	)		2.3
Adoption of Accounting Standards Update    2018-02		—			(16.2	)		(16.2	)		—			—			—
Net pension and postretirement benefits		(2.9	)		(15.6	)		(18.5	)		3.5			(1.2	)		2.3
Cumulative foreign currency translation adjustment:
Foreign currency translation recognized during    the period		(0.6	)		0.1			(0.5	)		7.8			(2.7	)		5.1
Adoption of Accounting Standards Update    2018-02		—			(3.9	)		(3.9	)		—			—			—
Net cumulative foreign currency translation    adjustment		(0.6	)		(3.8	)		(4.4	)		7.8			(2.7	)		5.1
Other comprehensive (loss) income	$	(303.0	)	$	75.0		$	(228.0	)	$	45.4		$	(19.0	)	$	26.4

Reclassifications Out of Accumulated Other Comprehensive Income

Reclassifications out of accumulated other comprehensive income were as follows:

	Three Months Ended
	March 31,
(in millions)	2018			2017
	Amount Reclassified from
Details about Accumulated Other	Accumulated Other						Affected Line Item in the Statement
Comprehensive Income Components	Comprehensive Income						Where Net Income is Presented
Unrealized gains on available-for-sale    securities	$	(0.2	)	$	4.1		Net realized (losses) gains from sales and other
		(0.5	)		(0.2	)	Net other-than-temporary impairment losses    on investments recognized in    earnings
		(0.7	)		3.9		Total before tax
		2.6			1.8		Tax benefit
		1.9			5.7		Net of tax
Amortization of defined benefit    pension and postretirement plans		(2.5	)		(3.5	)	Loss adjustment expenses and other    operating expenses
		0.5			1.2		Tax benefit
		(2.0	)		(2.3	)	Net of tax
Total reclassifications for the period	$	(0.1	)	$	3.4		(Expense) benefit to income, net of tax