Investments (Tables)

12 Months Ended

Dec. 31, 2022

Investments

Available-for-Sale Securities (Table)

			Gross		Gross		Allowance
	Amortized		unrealized		unrealized		for credit
	cost (1)		gains		losses		loss		Fair value
	(in millions)
December 31, 2022
Fixed maturities, available-for-sale:
U.S. government and agencies	$	1,964.6	$	0.1	$	248.8	$	—	$	1,715.9
Non-U.S. governments		565.3		18.9		63.8		—		520.4
States and political subdivisions		7,280.1		14.8		1,126.6		—		6,168.3
Corporate		37,495.4		219.5		4,530.1		—		33,184.8
Residential mortgage-backed pass-through securities		2,362.1		6.0		197.2		—		2,170.9
Commercial mortgage-backed securities		5,529.7		0.9		703.1		—		4,827.5
Collateralized debt obligations (2)		4,698.9		4.5		143.2		—		4,560.2
Other debt obligations		7,207.8		6.0		730.4		0.1		6,483.3
Total fixed maturities, available-for-sale	$	67,103.9	$	270.7	$	7,743.2	$	0.1	$	59,631.3
December 31, 2021
Fixed maturities, available-for-sale:
U.S. government and agencies	$	1,826.8	$	144.5	$	34.3	$	—	$	1,937.0
Non-U.S. governments		821.6		127.5		2.0		—		947.1
States and political subdivisions		8,210.3		1,022.4		16.3		—		9,216.4
Corporate		39,345.7		3,750.2		126.3		4.5		42,965.1
Residential mortgage-backed pass-through securities		2,296.9		57.6		12.2		—		2,342.3
Commercial mortgage-backed securities		5,388.6		156.3		30.9		0.3		5,513.7
Collateralized debt obligations (2)		3,539.1		4.0		9.6		—		3,533.5
Other debt obligations		7,368.3		130.6		57.0		0.1		7,441.8
Total fixed maturities, available-for-sale	$	68,797.3	$	5,393.1	$	288.6	$	4.9	$	73,896.9

(1) Amortized cost excludes accrued interest receivable of $575.8 million and $538.6 million as of December 31, 2022 and 2021, respectively.

(2) Primarily consists of collateralized loan obligations backed by secured corporate loans.

Fixed Maturities Available-for-Sale by Contractual Maturity (Table)

	Amortized cost		Fair value
	(in millions)
Due in one year or less	$	1,606.3	$	1,593.4
Due after one year through five years		8,297.6		7,950.4
Due after five years through ten years		11,046.5		10,029.5
Due after ten years		26,355.0		22,016.1
Subtotal		47,305.4		41,589.4
Mortgage-backed and other asset-backed securities		19,798.5		18,041.9
Total	$	67,103.9	$	59,631.3

Net Investment Income (Table)

	For the year ended December 31,
	2022		2021		2020
	(in millions)
Fixed maturities, available-for-sale	$	1,734.4	$	2,483.8	$	2,469.0
Fixed maturities, trading		19.6		8.7		9.2
Equity securities		(35.4)		1.7		3.3
Mortgage loans		619.9		692.4		669.8
Real estate		276.2		194.4		180.8
Policy loans		34.4		36.2		38.2
Cash and cash equivalents		37.6		1.7		9.5
Derivatives		171.3		28.2		(1.9)
Other		194.7		362.0		106.8
Total		3,052.7		3,809.1		3,484.7
Investment expenses		(200.4)		(175.4)		(159.8)
Net investment income	$	2,852.3	$	3,633.7	$	3,324.9

Net Realized Capital Gains and Losses (Table)

	For the year ended December 31,
	2022		2021		2020
	(in millions)
Fixed maturities, available-for-sale:
Gross gains	$	38.9	$	50.4	$	118.7
Gross losses		(120.7)		(26.9)		(45.0)
Net credit losses (1)		(11.5)		(34.5)		(22.6)
Hedging, net		(0.7)		(9.5)		(9.7)
Fixed maturities, trading (2)		(25.3)		(6.6)		6.2
Equity securities (3)		(7.4)		(0.5)		1.8
Mortgage loans		(74.1)		5.3		(14.3)
Derivatives		86.9		(4.2)		28.5
Other		112.7		8.0		42.0
Net realized capital gains (losses)	$	(1.2)	$	(18.5)	$	105.6

(1) Net credit losses include adjustments to the credit loss valuation allowance, write-offs and recoveries on available-for-sale securities.

(2) Unrealized gains (losses) on fixed maturities, trading still held at the reporting date were $(24.5) million, $(6.4) million and $6.9 million for the years ended December 31, 2022, 2021 and 2020, respectively. This excludes $1.4 million of unrealized losses on fixed maturities, trading still held at the reporting date for the year ended December 31, 2022, that were reported in net realized capital gains (losses) on funds withheld assets.

(3) Unrealized gains (losses) on equity securities still held at the reporting date were $(7.1) million, $(0.1) million and $1.9 million for the years ended December 31, 2022, 2021 and 2020, respectively. This excludes $1.7 million unrealized losses on equity securities still held at the reporting date for the year ended December 31, 2022, that were reported in net realized capital gains (losses) on funds withheld assets.

Allowance for credit loss (Tables)

	For the year ended December 31, 2022
									Residential
									mortgage-
									backed		Commercial		Collateralized
	U.S.				States and				pass-		mortgage-		debt		Other
	government		Non-U.S.		political				through		backed		obligations		debt
	and agencies		governments		subdivisions		Corporate		securities		securities		(1)		obligations		Total
	(in millions)
Beginning balance	$	—	$	—	$	—	$	4.5	$	—	$	0.3	$	—	$	0.1	$	4.9
Reductions for securities sold during the period		—		—		—		(8.7)		—		—		—		—		(8.7)
Additional increases (decreases) for credit losses on securities with an allowance recorded in the previous period		—		—		—		4.2		—		—		—		—		4.2
Write-offs charged against allowance		—		—		—		—		—		(0.3)		—		—		(0.3)
Ending balance	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	0.1	$	0.1

	For the year ended December 31, 2021
									Residential
									mortgage-
									backed		Commercial		Collateralized
	U.S.				States and				pass-		mortgage-		debt		Other
	government		Non-U.S.		political				through		backed		obligations		debt
	and agencies		governments		subdivisions		Corporate		securities		securities		(1)		obligations		Total
	(in millions)
Beginning balance	$	—	$	—	$	—	$	—	$	—	$	4.3	$	2.2	$	—	$	6.5
Additions for credit losses not previously recorded		—		—		—		16.9		—		0.4		—		0.1		17.4
Reductions for securities sold during the period		—		—		—		(12.4)		—		—		—		—		(12.4)
Additional increases (decreases) for credit losses on securities with an allowance recorded in the previous period		—		—		—		—		—		2.4		0.4		—		2.8
Write-offs charged against allowance		—		—		—		—		—		(6.8)		(2.6)		—		(9.4)
Ending balance	$	—	$	—	$	—	$	4.5	$	—	$	0.3	$	—	$	0.1	$	4.9
Accrued interest written off to net investment income	$	—	$	—	$	—	$	0.2	$	—	$	—	$	—	$	—	$	0.2

	For the year ended December 31, 2020
									Residential
									mortgage-
									backed		Commercial		Collateralized
	U.S.				States and				pass-		mortgage-		debt		Other
	government		Non-U.S.		political				through		backed		obligations		debt
	and agencies		governments		subdivisions		Corporate		securities		securities		(1)		obligations		Total
	(in millions)
Beginning balance (2)	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Additions for credit losses not previously recorded		—		—		—		7.0		—		2.9		0.1		—		10.0
Reductions for securities sold during the period		—		—		—		(7.0)		—		—		—		—		(7.0)
Additional increases (decreases) for credit losses on securities with an allowance recorded in the previous period		—		—		—		—		—		4.0		2.1		—		6.1
Write-offs charged against allowance		—		—		—		—		—		(2.6)		—		—		(2.6)
Ending balance	$	—	$	—	$	—	$	—	$	—	$	4.3	$	2.2	$	—	$	6.5

(1) Primarily consists of collateralized loan obligations backed by secured corporate loans.

(2) The allowance for credit loss associated with fixed maturities, available-for-sale was applied prospectively upon adoption of authoritative guidance effective January 1, 2020.

Available-for-Sale Securities in Unrealized Loss Positions Without an Allowance for Credit Loss (Table)

	December 31, 2022
	Less than				Greater than or
	twelve months				equal to twelve months				Total
			Gross				Gross				Gross
	Fair		unrealized		Fair		unrealized		Fair		unrealized
	value		losses		value		losses		value		losses
	(in millions)
Fixed maturities, available-for-sale (1):
U.S. government and agencies	$	1,505.5	$	207.0	$	180.4	$	41.8	$	1,685.9	$	248.8
Non-U.S. governments		373.0		56.7		19.9		7.1		392.9		63.8
States and political subdivisions		5,243.6		999.7		387.8		126.9		5,631.4		1,126.6
Corporate		26,668.2		3,875.1		2,625.4		654.9		29,293.6		4,530.0
Residential mortgage-backed pass-through securities		1,201.7		97.6		574.8		104.7		1,776.5		202.3
Commercial mortgage-backed securities		3,622.3		480.7		1,113.9		220.9		4,736.2		701.6
Collateralized debt obligations (2)		2,830.1		88.8		1,327.2		54.4		4,157.3		143.2
Other debt obligations		3,412.6		290.7		2,266.7		434.4		5,679.3		725.1
Total fixed maturities, available-for-sale	$	44,857.0	$	6,096.3	$	8,496.1	$	1,645.1	$	53,353.1	$	7,741.4

(1) Fair value and gross unrealized losses are excluded for available-for-sale securities for which an allowance for credit loss has been recorded.

(2) Primarily consists of collateralized loan obligations backed by secured corporate loans.

	December 31, 2021
	Less than				Greater than or
	twelve months				equal to twelve months				Total
			Gross				Gross				Gross
	Fair		unrealized		Fair		unrealized		Fair		unrealized
	value		losses		value		losses		value		losses
	(in millions)
Fixed maturities, available-for-sale (1):
U.S. government and agencies	$	128.2	$	3.4	$	386.3	$	30.9	$	514.5	$	34.3
Non-U.S. governments		57.5		2.0		—		—		57.5		2.0
States and political subdivisions		681.0		10.3		100.3		6.0		781.3		16.3
Corporate		4,538.4		59.0		1,252.3		67.1		5,790.7		126.1
Residential mortgage-backed pass- through securities		945.6		10.0		76.7		2.2		1,022.3		12.2
Commercial mortgage-backed securities		1,293.3		15.4		289.8		15.3		1,583.1		30.7
Collateralized debt obligations (2)		1,571.0		2.8		423.9		6.7		1,994.9		9.5
Other debt obligations		3,837.3		48.0		211.0		8.9		4,048.3		56.9
Total fixed maturities, available-for-sale	$	13,052.3	$	150.9	$	2,740.3	$	137.1	$	15,792.6	$	288.0

(1) Fair value and gross unrealized losses are excluded for available-for-sale securities for which an allowance for credit loss has been recorded.

(2) Primarily consists of collateralized loan obligations backed by secured corporate loans.

Net Unrealized Gains and Losses on Available-for-Sale Securities and Derivative Instruments (Table)

	December 31, 2022		December 31, 2021
	(in millions)
Net unrealized gains (losses) on fixed maturities, available-for-sale (1)	$	(7,552.8)	$	5,094.3
Net unrealized gains on derivative instruments		50.8		80.1
Adjustments for assumed changes in amortization patterns		649.7		(266.1)
Adjustments for assumed changes in policyholder liabilities		3.4		(664.8)
Net unrealized gains on other investments and noncontrolling interest adjustments		2.9		2.9
Provision for deferred income tax benefits (taxes)		1,464.1		(891.9)
Net unrealized gains (losses) on available-for-sale securities and derivative instruments	$	(5,381.9)	$	3,354.5

(1) Excludes net unrealized gains (losses) on fixed maturities, available-for-sale included in fair value hedging relationships.

Financing Receivable Credit Quality Indicators (Table)

	As of December 31, 2022
	2022		2021		2020		2019		2018		Prior		Total
		(in millions)
Commercial mortgage loans:
A- and above	$	995.9	$	2,182.5	$	1,753.8	$	2,177.2	$	2,130.8	$	4,555.1	$	13,795.3
BBB+ thru BBB-		371.8		412.8		149.7		391.6		222.6		676.4		2,224.9
BB+ thru BB-		104.0		—		—		—		8.9		66.5		179.4
B+ and below		—		—		—		—		8.3		35.5		43.8
Total	$	1,471.7	$	2,595.3	$	1,903.5	$	2,568.8	$	2,370.6	$	5,333.5	$	16,243.4
Residential mortgage loans:
Performing	$	1,101.4	$	1,669.1	$	364.5	$	99.2	$	51.2	$	253.6	$	3,539.0
Non-performing		8.0		4.7		1.8		1.0		0.6		4.4		20.5
Total	$	1,109.4	$	1,673.8	$	366.3	$	100.2	$	51.8	$	258.0	$	3,559.5
Reinsurance recoverable and deposit receivable													$	22,032.0

	As of December 31, 2021
	2021		2020		2019		2018		2017		Prior		Total
		(in millions)
Commercial mortgage loans:
A- and above	$	2,194.1	$	1,676.5	$	2,385.6	$	2,334.9	$	1,374.9	$	4,336.8	$	14,302.8
BBB+ thru BBB-		255.0		299.3		270.1		105.2		297.7		370.5		1,597.8
BB+ thru BB-		17.5		—		—		—		—		50.7		68.2
B+ and below		—		—		—		8.8		—		30.1		38.9
Total	$	2,466.6	$	1,975.8	$	2,655.7	$	2,448.9	$	1,672.6	$	4,788.1	$	16,007.7
Residential mortgage loans:
Performing	$	1,973.0	$	429.5	$	123.5	$	67.0	$	80.2	$	265.9	$	2,939.1
Non-performing		—		1.8		0.6		—		0.8		2.0		5.2
Total	$	1,973.0	$	431.3	$	124.1	$	67.0	$	81.0	$	267.9	$	2,944.3
Reinsurance recoverable and deposit receivable													$	1,189.0

Non-Accrual Financing Receivables (Table)

	December 31, 2022
					Amortized cost
	Beginning		Ending		of nonaccrual
	amortized cost		amortized cost		assets without
	on nonaccrual		on nonaccrual		a valuation
	status		status		allowance
	(in millions)
Commercial mortgage loans	$	8.7	$	43.8	$	—
Residential mortgage loans		3.4		16.0		0.6
Total	$	12.1	$	59.8	$	0.6

	December 31, 2021
					Amortized cost
	Beginning		Ending		of nonaccrual
	amortized cost		amortized cost		assets without
	on nonaccrual		on nonaccrual		a valuation
	status		status		allowance
	(in millions)
Commercial mortgage loans	$	—	$	8.7	$	—
Residential mortgage loans		9.1		3.4		0.7
Total	$	9.1	$	12.1	$	0.7

Schedule of Interest Income Recognized on Non-accrual Financing Receivables (Table)

	For the year ended December 31,
	2022		2021		2020
	(in millions)
Commercial mortgage loans	$	0.9	$	0.5	$	—
Total	$	0.9	$	0.5	$	—

Financing Receivables Aging (Table)

	December 31, 2022
					90 days or
	30-59 days		60-89 days		more past		Total
	past due		past due		due		past due		Current		Total(1)
	(in millions)
Commercial mortgage loans	$	—	$	—	$	8.3	$	8.3	$	16,235.1	$	16,243.4
Residential mortgage loans		35.9		2.4		12.4		50.7		3,508.8		3,559.5
Total	$	35.9	$	2.4	$	20.7	$	59.0	$	19,743.9	$	19,802.9

	December 31, 2021
					90 days or
	30-59 days		60-89 days		more past		Total
	past due		past due		due		past due		Current		Total(1)
	(in millions)
Commercial mortgage loans	$	—	$	—	$	—	$	—	$	16,007.7	$	16,007.7
Residential mortgage loans		27.6		2.9		4.5		35.0		2,909.3		2,944.3
Total	$	27.6	$	2.9	$	4.5	$	35.0	$	18,917.0	$	18,952.0

(1)     As of both December 31, 2022 and 2021, no reinsurance recoverables or deposit receivables were considered past due.

Financing Receivables Valuation Allowance (Table)

	For the year ended December 31, 2022
	Commercial		Residential		Reinsurance
	mortgage loans		mortgage loans		recoverables		Total
		(in millions)
Beginning balance	$	42.0	$	1.7	$	2.7	$	46.4
Provision		33.5		1.2		—		34.7
Charge-offs		—		(0.2)		—		(0.2)
Recoveries		—		2.3		—		2.3
Ending balance	$	75.5	$	5.0	$	2.7	$	83.2

	For the year ended December 31, 2021
	Commercial		Residential		Reinsurance
	mortgage loans		mortgage loans		recoverables		Total
		(in millions)
Beginning balance	$	40.5	$	5.7	$	2.7	$	48.9
Provision(1)		1.5		(7.2)		—		(5.7)
Charge-offs		—		(0.5)		—		(0.5)
Recoveries		—		3.7		—		3.7
Ending balance	$	42.0	$	1.7	$	2.7	$	46.4

	For the year ended December 31, 2020
	Commercial		Residential		Reinsurance
	mortgage loans		mortgage loans		recoverables		Total
		(in millions)
Beginning balance	$	25.9	$	2.6	$	2.5	$	31.0
Provision(2)		14.6		1.1		0.2		15.9
Charge-offs		—		(1.0)		—		(1.0)
Recoveries		—		3.0		—		3.0
Ending balance	$	40.5	$	5.7	$	2.7	$	48.9

(1) During the year ended December 31, 2021, certain valuation allowances for residential mortgage loans were released. This release was a result of further adjustments to our current and forecasted environmental factors management believed to be relevant as global economic activity improved from previously adverse impacts due to COVID-19.

(2) During the year ended December 31, 2020, COVID-19 adversely impacted global economic activity and contributed to significant volatility in financial markets. As a result, certain current and forecasted environmental factors management believed to be relevant were adjusted, resulting in an increase in the valuation allowance for commercial and residential mortgage loans.

Mortgage Loans Purchased and Sold (Table)

	For the year ended December 31,
	2022		2021		2020
	(in millions)
Commercial mortgage loans:
Purchased	$	261.3	$	—	$	45.7
Residential mortgage loans:
Purchased(1)		1,805.2		2,272.4		1,021.4
Sold		512.8		—		—

(1) Includes mortgage loans purchased by residential mortgage loan VIEs.

Commercial Mortgage Loans by Geographic Distribution and Property Type Distribution (Table)

	December 31, 2022				December 31, 2021
	Amortized		Percent		Amortized		Percent
	cost		of total		cost		of total
	($ in millions)
Geographic distribution
New England	$	513.3	3.2	%	$	587.1	3.7	%
Middle Atlantic		4,518.8	27.8			4,550.2	28.4
East North Central		653.9	4.0			625.3	3.9
West North Central		371.9	2.3			339.4	2.1
South Atlantic		2,565.5	15.8			2,471.9	15.4
East South Central		340.6	2.1			379.8	2.4
West South Central		1,208.8	7.4			1,247.8	7.8
Mountain		940.9	5.8			928.0	5.8
Pacific		5,129.7	31.6			4,878.2	30.5
Total	$	16,243.4	100.0	%	$	16,007.7	100.0	%
Property type distribution
Office	$	4,331.8	26.7	%	$	4,801.0	29.9	%
Retail		1,502.5	9.2			1,625.5	10.2
Industrial		3,246.4	20.0			2,975.7	18.6
Apartments		6,848.3	42.2			6,255.2	39.1
Hotel		72.5	0.4			85.7	0.5
Mixed use/other		241.9	1.5			264.6	1.7
Total	$	16,243.4	100.0	%	$	16,007.7	100.0	%

Mortgage Loans Modified as a Troubled Debt Restructuring (Table)

	For the year ended December 31, 2022
	TDRs			TDRs in payment default
	Number of	Recorded		Number of	Recorded
	contracts	investment		contracts	investment
			(in millions)			(in millions)
Commercial mortgage loans	1	$	35.5	—	$	—
Total	1	$	35.5	—	$	—

Minority Interests in Unconsolidated Entities-Balance Sheet (Table)

	December 31,
	2022		2021
	(in millions)
Total assets	$	128,765.7	$	106,743.2
Total liabilities		12,335.4		11,862.3
Total equity	$	116,430.3	$	94,880.9
Net investment in unconsolidated entities	$	1,275.5	$	957.1

Minority Interests in Unconsolidated Entities-Income Statement (Table)

	For the year ended
	December 31,
	2022		2021		2020
	(in millions)
Total revenues	$	36,915.1	$	17,674.2	$	11,761.4
Net income		33,194.6		14,083.1		7,350.8
Our share of net income of unconsolidated entities		119.5		229.6		46.4

Financial Assets Subject to Netting Agreements (Table)

			Gross amounts not offset in the
			consolidated statements
			of financial position
	Gross amount
	of recognized		Financial		Collateral
	assets(1)		instruments(2)		received		Net amount
	(in millions)
December 31, 2022
Derivative assets	$	256.6	$	(133.5)	$	(120.8)	$	2.3
Reverse repurchase agreements		112.9		—		(112.9)		—
Total	$	369.5	$	(133.5)	$	(233.7)	$	2.3
December 31, 2021
Derivative assets	$	326.2	$	(99.6)	$	(219.2)	$	7.4

(1) The gross amount of recognized derivative assets is reported with other investments on the consolidated statements of financial position. The gross amounts of derivative assets are not netted against offsetting liabilities for presentation on the consolidated statements of financial position.

(2) Represents amount of offsetting derivative liabilities that are subject to an enforceable master netting agreement or similar agreement that are not netted against the gross derivative assets for presentation on the consolidated statements of financial position.

Financial Liabilities Subject to Netting Agreements (Table)

			Gross amounts not offset in the
			consolidated statements
			of financial position
	Gross amount
	of recognized		Financial		Collateral
	liabilities(1)		instruments(2)		pledged		Net amount
	(in millions)
December 31, 2022
Derivative liabilities	$	612.3	$	(133.5)	$	(467.2)	$	11.6
December 31, 2021
Derivative liabilities	$	142.3	$	(99.6)	$	(41.9)	$	0.8

(1) The gross amount of recognized derivative liabilities is reported with other liabilities on the consolidated statements of financial position. The above excludes derivative liabilities, which are primarily embedded derivatives that are not subject to master netting agreements or similar agreements. The gross amounts of derivative liabilities are not netted against offsetting assets for presentation on the consolidated statements of financial position.

(2) Represents amount of offsetting derivative assets that are subject to an enforceable master netting agreement or similar agreement that are not netted against the gross derivative liabilities for presentation on the consolidated statements of financial position.