Fair Value (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Values of Financial Instruments

The estimated fair values of the financial instruments were as follows:

	December 31, 2020				December 31, 2019
	Carrying		Fair		Carrying		Fair
(in millions)	Value		Value		Value		Value
Financial Assets carried at:
Fair Value through AOCI:
Fixed maturities	$	7,454.4	$	7,454.4	$	6,687.1	$	6,687.1
Fair Value through Net Income:
Equity securities		598.5		598.5		575.7		575.7
Other investments		176.8		176.8		187.1		187.1
Amortized Cost/Cost:
Other investments		470.3		504.8		443.3		463.7
Cash and cash equivalents		120.6		120.6		215.7		215.7
Total financial instruments	$	8,820.6	$	8,855.1	$	8,108.9	$	8,129.3
Financial Liabilities carried at:
Amortized Cost:
Debt	$	780.8	$	887.7	$	653.4	$	722.1

Fair Value, Investment Assets Measured on Recurring Basis

The following tables provide, for each hierarchy level, the Company’s investment assets that were measured at fair value on a recurring basis.

	DECEMBER 31, 2020
(in millions)	Total		Level 1		Level 2		Level 3
Fixed maturities:
U.S. Treasury and government agencies	$	392.0	$	155.8	$	236.2	$	—
Foreign government		2.7		—		2.7		—
Municipal		1,103.7		—		1,096.7		7.0
Corporate		4,111.3		—		4,110.8		0.5
Residential mortgage-backed		1,010.7		—		1,010.7		—
Commercial mortgage-backed		760.0		—		747.6		12.4
Asset-backed		74.0		—		74.0		—
Total fixed maturities		7,454.4		155.8		7,278.7		19.9
Equity securities		598.5		593.0		—		5.5
Other investments		4.0		—		—		4.0
Total investment assets at fair value	$	8,056.9	$	748.8	$	7,278.7	$	29.4

	DECEMBER 31, 2019
(in millions)	Total		Level 1		Level 2		Level 3
Fixed maturities:
U.S. Treasury and government agencies	$	349.8	$	157.9	$	191.9	$	—
Foreign government		16.1		—		16.1		—
Municipal		833.5		—		821.4		12.1
Corporate		3,811.2		—		3,810.6		0.6
Residential mortgage-backed		921.4		—		921.4		—
Commercial mortgage-backed		691.9		—		679.2		12.7
Asset-backed		63.2		—		63.2		—
Total fixed maturities		6,687.1		157.9		6,503.8		25.4
Equity securities		575.7		573.6		—		2.1
Other investments		3.5		—		—		3.5
Total investment assets at fair value	$	7,266.3	$	731.5	$	6,503.8	$	31.0

Estimated Fair Values of Financial Instruments Not Carried at Fair Value

The following tables provide, for each hierarchy level, the Company’s estimated fair values of financial instruments that were not carried at fair value.  

	DECEMBER 31, 2020
(in millions)	Total		Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	120.6	$	120.6	$	—	$	—
Other investments		504.8		—		2.7		502.1
Total financial instruments	$	625.4	$	120.6	$	2.7	$	502.1
Liabilities:
Debt	$	887.7	$	—	$	887.7	$	—

	DECEMBER 31, 2019
(in millions)	Total		Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	215.7	$	215.7	$	—	$	—
Other investments		463.7		—		2.1		461.6
Total financial instruments	$	679.4	$	215.7	$	2.1	$	461.6
Liabilities:
Debt	$	722.1	$	—	$	722.1	$	—

Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)

The following tables provide a reconciliation for all assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3).

YEAR ENDED DECEMBER 31, 2020	Fixed Maturities
(in millions)	Municipal			Corporate			Commercial mortgage- backed			Total			Equity and Other		Total Assets
Balance at beginning of year	$	12.1		$	0.6		$	12.7		$	25.4		$	5.6	$	31.0
Transfers out of Level 3		(3.5	)		—			—			(3.5	)		—		(3.5	)
Total gains:
Included in total net realized and   unrealized investment gains		—			—			—			—			3.9		3.9
Included in other comprehensive    income - net appreciation on    available-for-sale securities		0.1			—			0.7			0.8			—		0.8
Sales		(1.7	)		(0.1	)		(1.0	)		(2.8	)		—		(2.8	)
Balance at end of year	$	7.0		$	0.5		$	12.4		$	19.9		$	9.5	$	29.4
Changes in unrealized gains for the period    included in other comprehensive income    for assets held at the end of the year	$	0.3		$	—		$	0.7		$	1.0		$	—	$	1.0

YEAR ENDED DECEMBER 31, 2019	Fixed Maturities
(in millions)	Municipal			Corporate			Commercial mortgage- backed			Total			Equity and Other		Total Assets
Balance at beginning of year	$	21.1		$	0.8		$	13.1		$	35.0		$	4.6	$	39.6
Total gains:
Included in other comprehensive    income - net appreciation on    available-for-sale securities		0.9			—			0.5			1.4			—		1.4
Purchases and sales:
Purchases		—			—			—			—			1.0		1.0
Sales		(9.9	)		(0.2	)		(0.9	)		(11.0	)		—		(11.0	)
Balance at end of year	$	12.1		$	0.6		$	12.7		$	25.4		$	5.6	$	31.0

Schedule of Additional Information About Significant Unobservable Inputs Used in Fair Valuations of Level 3

The following table provides quantitative information about the significant unobservable inputs used by the Company in the fair value measurements of Level 3 assets. Where discounted cash flows were used in the valuation of fixed maturities, the internally-developed discount rate was adjusted by the significant unobservable inputs shown in the table. 

DECEMBER 31,			2020				2019
	Valuation	Significant	Fair		Range		Fair		Range
(in millions)	Technique	Unobservable Inputs	Value		(Wtd Average)		Value		(Wtd Average)
Fixed maturities:
Municipal	Discounted	Discount for:	$	7.0			$	12.1
	cash flow	Small issue size			0.7 - 6.8% (5.0%)				0.7 - 6.8% (4.3%)
		Credit stress			0.2% (0.2%)					—
		Above-market coupon				—			0.5% (0.5%)
Corporate	Discounted	Discount for:		0.5			0.6
	cash flow	Small issue size			2.5% (2.5%)				2.5% (2.5%)
		Above-market coupon			0.3% (0.3%)				0.3% (0.3%)
Commercial	Discounted	Discount for:		12.4			12.7
mortgage-backed	cash flow	Small issue size			1.9 - 3.1% (2.7%)				1.9 - 3.1% (2.7%)
		Above-market coupon			0.5% (0.5%)				0.5% (0.5%)
		Lease structure			0.3% (0.3%)				0.3% (0.3%)
		Credit stress			0.2% (0.2%)					—
Equity securities	Market comparables	Net tangible asset    market multiples		1.1	1.0X (1.0X)		1.1		1.0X (1.0X)
	Internal price	Unadjusted price from        financing round		4.4	5.60 (5.60)		1.0		1.27 (1.27)
Other	Discounted cash flow	Discount rate		4.0	16.2% (16.2%)		3.5		18.0% (18.0%)