Accumulated Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 692.5		$ 732.4		$ 733.9
Other comprehensive income (loss), net of tax		6.9		15.0		19.9
Ending balance		631.2		692.5		732.4
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(21.4)		(19.8)		(33.2)
Less: income tax (expense) benefit	[1]	(1.2)		(0.9)		(1.2)
Net loss (gain) reclassified from AOCI to Net (loss) income		3.7		3.0		3.9
Translation impact on Canadian pension plan AOCI balance						(0.1)
Other comprehensive income (loss), net of tax		24.2		(1.6)		13.4
Ending balance		2.8		(21.4)		(19.8)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Unrealized gain (loss) on securities		27.0		8.0		0.4
Less: income tax benefit (expense)		(6.5)		(1.9)		(0.1)
Net unrealized gain (loss) on available for sale securities, cash flow hedges and fair value hedges		20.5		6.1		0.3
Reclassification from AOCI	[2]			0.4		0.4
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Unrealized gain (loss) on securities				(14.0)		12.3
Less: income tax benefit (expense)				3.3		(3.0)
Net unrealized gain (loss) on available for sale securities, cash flow hedges and fair value hedges				(10.7)		9.3
Reclassification from AOCI	[2]	4.9		3.5		4.7
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		17.7	[3]	1.1	[3]	(5.6)
Unrealized gain (loss) on securities		(12.2)		63.6		(9.4)
Less: income tax benefit (expense)		2.9		(15.0)		2.3
Net unrealized gain (loss) on available for sale securities, cash flow hedges and fair value hedges		(9.3)		48.6		(7.1)
Reclassification from AOCI		(10.5)		(41.9)		17.4
Reclassification due to forecasted transactions no longer probable of occurring						0.8
Less: income tax (expense) benefit	[1]	2.5		9.9		(4.4)
Net loss (gain) reclassified from AOCI to Net (loss) income		(8.0)		(32.0)		13.8
Other comprehensive income (loss), net of tax		(17.3)		16.6		6.7
Ending balance	[3]	0.4		17.7		1.1
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance						0.3
Unrealized gain (loss) on securities						1.3
Less: income tax benefit (expense)						(0.7)
Net unrealized gain (loss) on available for sale securities, cash flow hedges and fair value hedges						0.6
Reclassification from AOCI	[4]					(2.0)
Less: income tax (expense) benefit	[1]					1.1
Net loss (gain) reclassified from AOCI to Net (loss) income						(0.9)
Other comprehensive income (loss), net of tax						(0.3)
AOCI, Excluded Component of Derivative Qualifying as Fair Value Hedge Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Unrealized gain (loss) on securities						(1.0)
Less: income tax benefit (expense)						0.2
Net unrealized gain (loss) on available for sale securities, cash flow hedges and fair value hedges						(0.8)
Reclassification from AOCI						0.4
Reclassification due to cancellation of firm commitment						0.6
Less: income tax (expense) benefit	[1]					(0.2)
Net loss (gain) reclassified from AOCI to Net (loss) income						0.8
AOCI, Accumulated Foreign Currency Adjustment Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance						(0.1)
Other comprehensive income (loss), net of tax						0.1
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(3.7)		(18.7)		(38.6)
Other comprehensive income (loss), net of tax		6.9		15.0		19.9
Ending balance		$ 3.2		$ (3.7)		$ (18.7)

[1] Income tax amounts reclassified out of AOCI were included as a component of Income tax benefit (provision).

[2] Amounts amortized out of AOCI related to pension and other postretirement benefits were included within Net periodic postretirement benefit cost (see Note 5).

[3] As of December 31, 2022, we estimate a net mark-to-market loss before tax of $1.7 million in AOCI will be reclassified into Net (loss) income upon settlement within the next 12 months.

[4] Amounts reclassified out of AOCI relating to sales of available for sale securities were included as a component of Other income (expense), net. We use the specific identification method to determine the amount reclassified out of AOCI.