BUSINESS SEGMENTS - RECONCILIATION OF OPERATING PROFIT (LOSS) FROM SEGMENTS TO CONSOLIDATED (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Total segment revenues									$ 3,667.0	$ 4,076.1	$ 3,807.5
Total investment gains (losses)									(17.9)	21.3	(18.4)
Total revenues	$ 973.6	$ 905.3	$ 855.0	$ 842.9	$ 1,074.8	$ 968.3	$ 1,073.1	$ 1,006.0	3,576.8	4,122.2	3,821.1
Total segment expenses									3,309.9	3,605.5	3,343.7
Other operating expenses									954.6	987.3	942.0
Total benefits and expenses									3,059.5	3,554.5	3,476.8
Income before income taxes	55.4	137.2	175.4	149.3	148.1	128.0	101.6	190.0	517.3	567.7	344.3
Income tax expense (benefit):
Income tax expense on period income									120.5	126.7	76.5
Valuation allowance for deferred tax assets and other tax items									0.0	0.0	(34.0)
Net income	$ 43.4	$ 105.0	$ 136.1	$ 112.3	$ 115.8	$ 99.8	$ 78.0	$ 147.4	396.8	441.0	301.8
Operating segments
Segment Reporting Information [Line Items]
Total segment revenues									3,667.0	4,076.1	3,807.5
Total segment expenses									3,309.9	3,605.5	3,343.7
Segment reconciling items
Segment Reporting Information [Line Items]
Total investment gains (losses)									(135.4)	19.1	(36.2)
Revenues related to earnings attributable to VIEs									45.2	27.0	35.5
Fee revenue related to transition services agreement									0.0	0.0	14.3
Insurance policy benefits - fair value changes in embedded derivative liabilities									(340.9)	(90.1)	99.0
Amortization related to fair value changes in embedded derivative liabilities									93.7	22.9	(19.9)
Amortization related to investment gains (losses)									(3.4)	1.7	(2.4)
Expenses attributable to VIEs									43.0	24.4	33.8
Fair value changes related to agent deferred compensation plan									(48.9)	(8.9)	16.3
Expenses related to transition services agreement									0.0	0.0	8.8
Other operating expenses									$ 6.1	$ (1.0)	$ (2.5)