Long-Duration Insurance Contracts - Balances of and Changes in the LFPB (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Dec. 31, 2020
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Liability for future policy benefits	$ 1,740.9	$ 1,740.9	$ 1,718.0
Previously Reported
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Liability for future policy benefits
Whole Life
Present Value of Expected Net Premiums
Beginning balance	222.2	215.1	183.0	$ 176.5
Beginning period (including reserves)				260.7
Beginning balance at original discount rate	246.6	245.9	157.6	143.5
Beginning balance at original discount rate (including reserves)			239.3
Change in cash flow assumptions			0.0	5.2	$ 0.0	$ 2.4
Actual variances from expected experience			1.8	7.2	1.0	8.8
Adjusted balance			247.7	251.7	247.6	154.7
Issuances	2.6	5.4	12.5	13.3
Interest accruals	1.8	3.6	6.7	6.2
Net premiums collected	(5.0)	(9.7)	(25.0)	(16.6)
Ending balance at original discount rate	247.0	247.0	245.9	157.6
Effect of changes in discount rate assumptions	(29.5)	(29.5)	(30.8)	25.4
Ending balance	217.5	217.5	215.1	183.0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	515.1	493.6	500.7	507.1
Beginning balance (including reserves)			660.4
Beginning balance at original discount rate	588.7	588.7	581.9	386.3	585.4	362.5
Beginning balance at original discount rate (including reserves)			566.1
Changes in cash flow assumptions			0.0	5.2	0.0	2.8
Actual variances from expected experience			1.9	7.7	1.1	8.7
Adjusted balance			583.8	579.0	586.5	374.0
Issuances	2.6	5.5	12.4	13.3
Interest accruals	4.7	9.4	18.0	17.1
Benefit payments	(5.1)	(10.0)	(27.5)	(18.1)
Ending balance at original discount rate	588.7	588.7	581.9	386.3
Effect of changes in discount rate assumptions	(81.6)	(81.6)	(88.3)	114.4
Ending balance	507.1	507.1	493.6	500.7
Ending balance (including reserves)				660.4
Liability for future policy benefits	289.4	289.4	278.4	317.7		330.6
Less: Reinsurance recoverable	(63.1)	(63.1)	(63.1)	(0.5)		(0.1)
Less: Change in discount rate assumptions						(0.2)
Net liability for future policy benefits, after reinsurance recoverable	226.3	226.3	215.3
Impact of flooring on net liability for future policy benefits	0.0	0.0	1.1
Net liability for future policy benefits at June 30, 2023	226.3	226.3	216.4	317.2		330.3
Whole Life | Previously Reported
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Liability for future policy benefits						218.7
Whole Life | Change in discount rate assumptions
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						111.5
Whole Life | Change in cash flow assumptions, effect of net premiums exceeding gross premiums
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.4
Whole Life | Change in cash flow assumptions, effect of decrease of the DPL
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Whole Life | Adjustment for removal of related balances in AOCI
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Term Life
Present Value of Expected Net Premiums
Beginning balance	243.8	234.7	253.1	244.1
Beginning period (including reserves)				264.4
Beginning balance at original discount rate	266.0	265.4	221.1	200.8
Beginning balance at original discount rate (including reserves)			235.4
Change in cash flow assumptions			(5.3)	18.7	(5.3)	(4.5)
Actual variances from expected experience			(1.0)	(4.2)	0.5	6.9
Adjusted balance			259.1	249.9	261.2	203.2
Issuances	6.5	13.0	28.0	29.8
Interest accruals	2.7	5.2	9.0	7.9
Net premiums collected	(5.3)	(12.2)	(21.5)	(19.8)
Ending balance at original discount rate	265.1	265.1	265.4	221.1
Effect of changes in discount rate assumptions	(24.8)	(24.8)	(30.7)	32.0
Ending balance	240.3	240.3	234.7	253.1
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	365.0	347.0	370.6	364.7
Beginning balance (including reserves)			411.5
Beginning balance at original discount rate	406.4	406.4	401.0	319.5	405.2	294.0
Beginning balance at original discount rate (including reserves)			360.0
Changes in cash flow assumptions			(5.6)	21.5	(5.6)	(4.8)
Actual variances from expected experience			0.7	(4.7)	2.2	7.2
Adjusted balance			396.1	376.8	401.8	296.4
Issuances	6.6	13.2	28.3	29.8
Interest accruals	3.5	7.5	14.4	12.0
Benefit payments	(5.5)	(10.4)	(18.5)	(18.7)
Ending balance at original discount rate	406.4	406.4	401.0	319.5
Effect of changes in discount rate assumptions	(45.8)	(45.8)	(54.0)	51.1
Ending balance	360.6	360.6	347.0	370.6
Ending balance (including reserves)				411.5
Liability for future policy benefits	120.3	120.3	112.2	117.6		120.5
Less: Reinsurance recoverable	(16.7)	(16.7)	(15.3)	(5.5)		(5.4)
Less: Change in discount rate assumptions						(0.9)
Net liability for future policy benefits, after reinsurance recoverable	103.6	103.6	96.9
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.2
Net liability for future policy benefits at June 30, 2023	103.6	103.6	97.1	112.1		114.2
Term Life | Previously Reported
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Liability for future policy benefits						93.2
Term Life | Change in discount rate assumptions
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						27.3
Term Life | Change in cash flow assumptions, effect of net premiums exceeding gross premiums
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Term Life | Change in cash flow assumptions, effect of decrease of the DPL
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Term Life | Adjustment for removal of related balances in AOCI
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Experience Life
Present Value of Expected Net Premiums
Beginning balance	69.8	68.3	74.6	78.0
Beginning period (including reserves)				74.6
Beginning balance at original discount rate	65.0	65.5	55.8	55.2
Beginning balance at original discount rate (including reserves)			55.9
Change in cash flow assumptions			0.0	9.1	0.0	(3.3)
Actual variances from expected experience			0.7	3.0	0.5	6.3
Adjusted balance			66.2	68.0	65.5	58.2
Issuances	0.0	0.0	0.0	0.0
Interest accruals	0.8	1.8	3.3	3.2
Net premiums collected	(1.6)	(3.3)	(5.8)	(5.6)
Ending balance at original discount rate	64.7	64.7	65.5	55.8
Effect of changes in discount rate assumptions	3.4	3.4	2.8	18.8
Ending balance	68.1	68.1	68.3	74.6
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	892.5	867.5	1,172.7	1,269.3
Beginning balance (including reserves)			1,172.7
Beginning balance at original discount rate	799.6	799.6	805.2	802.5	801.5	813.5
Beginning balance at original discount rate (including reserves)			802.6
Changes in cash flow assumptions			0.0	11.0	0.0	(3.6)
Actual variances from expected experience			0.9	3.6	0.5	6.6
Adjusted balance			806.1	817.2	802.0	816.5
Issuances	0.0	0.0	0.0	0.0
Interest accruals	11.9	23.8	47.4	47.9
Benefit payments	(14.3)	(30.3)	(59.4)	(61.9)
Ending balance at original discount rate	799.6	799.6	805.2	802.5
Effect of changes in discount rate assumptions	71.9	71.9	62.3	370.2
Ending balance	871.5	871.5	867.5	1,172.7
Ending balance (including reserves)				1,172.7
Liability for future policy benefits	803.5	803.5	799.3	1,098.1		1,191.3
Less: Reinsurance recoverable	(0.7)	(0.7)	(0.8)	(1.1)		(1.3)
Less: Change in discount rate assumptions						(0.7)
Net liability for future policy benefits, after reinsurance recoverable	802.8	802.8	798.5
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits at June 30, 2023	802.8	802.8	798.5	1,097.0		1,189.3
Experience Life | Previously Reported
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Liability for future policy benefits						758.3
Experience Life | Change in discount rate assumptions
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						433.0
Experience Life | Change in cash flow assumptions, effect of net premiums exceeding gross premiums
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Experience Life | Change in cash flow assumptions, effect of decrease of the DPL
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Experience Life | Adjustment for removal of related balances in AOCI
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Limited Pay Whole Life
Present Value of Expected Net Premiums
Beginning balance	31.2	29.7	29.7	25.4
Beginning period (including reserves)				29.7
Beginning balance at original discount rate	33.1	32.4	27.2	22.0
Beginning balance at original discount rate (including reserves)			27.2
Change in cash flow assumptions			0.0	2.0	0.0	0.0
Actual variances from expected experience			1.3	1.6	0.8	1.0
Adjusted balance			33.7	30.8	33.9	23.0
Issuances	1.1	2.1	6.3	10.2
Interest accruals	0.3	0.6	1.1	0.8
Net premiums collected	(1.1)	(2.2)	(5.8)	(6.8)
Ending balance at original discount rate	34.2	34.2	32.4	27.2
Effect of changes in discount rate assumptions	(2.5)	(2.5)	(2.7)	2.5
Ending balance	31.7	31.7	29.7	29.7
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	84.4	79.4	102.9	95.0
Beginning balance (including reserves)			102.9
Beginning balance at original discount rate	102.6	102.6	98.6	86.6	100.3	73.4
Beginning balance at original discount rate (including reserves)			86.6
Changes in cash flow assumptions			0.0	2.0	0.0	0.0
Actual variances from expected experience			1.5	1.4	0.9	1.1
Adjusted balance			100.1	90.0	101.2	74.5
Issuances	1.1	2.1	6.4	10.2
Interest accruals	1.0	1.9	3.4	2.9
Benefit payments	(0.7)	(1.5)	(1.2)	(1.0)
Ending balance at original discount rate	102.6	102.6	98.6	86.6
Effect of changes in discount rate assumptions	(17.3)	(17.3)	(19.2)	16.3
Ending balance	85.3	85.3	79.4	102.9
Ending balance (including reserves)				102.9
Liability for future policy benefits	53.7	53.7	49.6	73.2		69.5
Less: Reinsurance recoverable	(0.2)	(0.2)	0.0	(0.2)		(0.1)
Less: Change in discount rate assumptions						(0.1)
Net liability for future policy benefits, after reinsurance recoverable	53.5	53.5	49.6
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits at June 30, 2023	53.5	53.5	49.6	73.0		69.3
Limited Pay Whole Life | Previously Reported
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Liability for future policy benefits						51.3
Limited Pay Whole Life | Change in discount rate assumptions
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						18.2
Limited Pay Whole Life | Change in cash flow assumptions, effect of net premiums exceeding gross premiums
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Limited Pay Whole Life | Change in cash flow assumptions, effect of decrease of the DPL
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Limited Pay Whole Life | Adjustment for removal of related balances in AOCI
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Supplemental health
Present Value of Expected Net Premiums
Beginning balance	172.5	167.4	221.5	233.0
Beginning period (including reserves)				226.7
Beginning balance at original discount rate	205.1	205.1	217.5	218.2
Beginning balance at original discount rate (including reserves)			223.1
Change in cash flow assumptions			0.0	12.2	0.0	(1.8)
Actual variances from expected experience			0.3	(25.3)	1.7	6.3
Adjusted balance			205.4	210.0	206.8	222.7
Issuances	4.6	9.9	12.0	13.0
Interest accruals	1.5	3.0	5.9	5.9
Net premiums collected	(5.4)	(10.8)	(22.8)	(24.1)
Ending balance at original discount rate	207.5	207.5	205.1	217.5
Effect of changes in discount rate assumptions	(35.5)	(35.5)	(37.7)	4.0
Ending balance	172.0	172.0	167.4	221.5
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	437.7	431.7	580.6	626.9
Beginning balance (including reserves)			590.6
Beginning balance at original discount rate	525.8	525.8	537.1	572.6	530.6	589.1
Beginning balance at original discount rate (including reserves)			584.2
Changes in cash flow assumptions			0.0	13.8	0.0	(3.0)
Actual variances from expected experience			0.1	(30.0)	1.8	6.2
Adjusted balance			537.2	568.0	532.4	592.3
Issuances	4.6	9.9	12.0	13.0
Interest accruals	3.6	7.2	15.0	15.7
Benefit payments	(14.8)	(28.5)	(57.9)	(48.4)
Ending balance at original discount rate	525.8	525.8	537.1	572.6
Effect of changes in discount rate assumptions	(99.2)	(99.2)	(105.4)	8.0
Ending balance	426.6	426.6	431.7	580.6
Ending balance (including reserves)				590.6
Liability for future policy benefits	254.5	254.5	264.4	359.1		415.5
Less: Reinsurance recoverable	(3.9)	(3.9)	(3.4)	0.0		0.0
Less: Change in discount rate assumptions						0.0
Net liability for future policy benefits, after reinsurance recoverable	250.6	250.6	261.0
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits at June 30, 2023	250.6	250.6	261.0	359.1		415.5
Supplemental health | Previously Reported
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Liability for future policy benefits						392.5
Supplemental health | Change in discount rate assumptions
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						23.0
Supplemental health | Change in cash flow assumptions, effect of net premiums exceeding gross premiums
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Supplemental health | Change in cash flow assumptions, effect of decrease of the DPL
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Supplemental health | Adjustment for removal of related balances in AOCI
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
Cancer
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits at June 30, 2023	97.3	97.3	101.8	140.8		163.5
Accident
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits at June 30, 2023	21.5	21.5	21.8	28.7		31.2
Disability
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits at June 30, 2023	22.9	22.9	23.1	29.3		32.0
Other
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits at June 30, 2023	108.9	108.9	114.3	160.3		188.8
SPIA (life contingent)
Present Value of Expected Net Premiums
Beginning balance	0.0	0.0	0.0	0.0
Beginning period (including reserves)				0.0
Beginning balance at original discount rate	0.0	0.0	0.0	0.0
Beginning balance at original discount rate (including reserves)			0.0
Change in cash flow assumptions			0.0	0.0	0.0	0.0
Actual variances from expected experience			0.0	0.0	0.0	0.0
Adjusted balance			0.0	0.0	0.0	0.0
Issuances	1.4	3.4	5.3	3.7
Interest accruals	0.0	0.0	0.0	0.0
Net premiums collected	(1.4)	(3.4)	(5.3)	(3.7)
Ending balance at original discount rate	0.0	0.0	0.0	0.0
Effect of changes in discount rate assumptions	0.0	0.0	0.0	0.0
Ending balance	0.0	0.0	0.0	0.0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	105.9	103.3	124.7	136.5
Beginning balance (including reserves)			129.1
Beginning balance at original discount rate	113.0	113.0	113.4	111.6	113.3	115.9
Beginning balance at original discount rate (including reserves)			115.7
Changes in cash flow assumptions			0.0	0.0	0.0	0.0
Actual variances from expected experience			(0.5)	0.4	0.0	(0.4)
Adjusted balance			112.9	116.1	$ 113.3	115.5
Issuances	1.6	4.0	5.3	3.7
Interest accruals	1.1	2.2	4.3	4.5
Benefit payments	(3.0)	(6.1)	(12.3)	(12.1)
Ending balance at original discount rate	113.0	113.0	113.4	111.6
Effect of changes in discount rate assumptions	(9.4)	(9.4)	(10.1)	13.1
Ending balance	103.6	103.6	103.3	124.7
Ending balance (including reserves)				129.1
Liability for future policy benefits	103.6	103.6	103.3	124.7		136.5
Less: Reinsurance recoverable	(3.5)	(3.5)	(3.2)	0.0		0.0
Less: Change in discount rate assumptions						0.0
Net liability for future policy benefits, after reinsurance recoverable	100.1	100.1	100.1
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits at June 30, 2023	$ 100.1	$ 100.1	$ 100.1	$ 124.7		136.5
SPIA (life contingent) | Previously Reported
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Liability for future policy benefits						115.9
SPIA (life contingent) | Change in discount rate assumptions
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						20.6
SPIA (life contingent) | Change in cash flow assumptions, effect of net premiums exceeding gross premiums
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
SPIA (life contingent) | Change in cash flow assumptions, effect of decrease of the DPL
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						0.0
SPIA (life contingent) | Adjustment for removal of related balances in AOCI
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Changes in cash flow assumptions						$ 0.0