Schedule 2 - Parent Company Financial Statements - Statements of Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Condensed Statement of Income Captions [Line Items]
Net Loss	$ (272.3)	$ (286.6)	[1]	$ (123.7)	[1]
Reclassification Adjustment for Postretirement Benefit Costs Arising During the Year:
Net Unrecognized Postretirement Benefit Costs	59.2	18.9		(8.8)
Gains on Cash Flow Hedge	(0.2)	5.9		0.5
Other Comprehensive Income (Loss) Before Income Taxes	195.6	(143.7)		(66.3)
Reclassification Adjustment for Amounts Included in Net Loss:
Unrealized Holding Gains and Losses	(50.3)	325.5		60.7
Reclassification Adjustments for Amounts Included in Net Loss:
Debt Extinguishment, Pension Settlement, and Other Charges	(70.2)
Change in Discount Rate on Future Life Policyholder Benefits	21.2	(289.9)		(47.9)
Changes in Gain on Cash Flow Hedges	0.2	(5.9)		(0.5)
Other Comprehensive Income Tax Benefit (Expense)	(41.5)	30.4		14.5
Other Comprehensive Income (Loss), Net of Taxes	154.1	(113.3)		(51.8)
Total Comprehensive Loss	(118.2)	(399.9)		(175.5)
Less: Total Comprehensive Loss attributable to Noncontrolling Interest	(0.2)	0.0		0.0
Comprehensive Loss attributable to Kemper Corporation	(118.0)	(399.9)		(175.5)
Credit Losses
Reclassification Adjustment for Amounts Included in Net Loss:
Changes in Net Unrealized Holding Gains (Losses) on Investment Securities	(0.5)	1.9		(2.0)
No Credit Losses
Reclassification Adjustment for Amounts Included in Net Loss:
Changes in Net Unrealized Holding Gains (Losses) on Investment Securities	238.8	(1,551.1)		(284.5)
Subsidiaries
Reclassification Adjustment for Amounts Included in Net Loss:
Reclassification Adjustment for Amounts Included in Net Income	4.5	(12.8)		(43.5)
Unrecognized Postretirement Benefit Costs Arising During the Year	0.1	1.1		0.6
Reclassification Adjustment for Amounts Included in Net Loss:
Reclassification Adjustment for Amounts Included in Net Income	(1.0)	2.7		9.1
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax	0.0	(0.2)		(0.1)
Reclassification Adjustments for Amounts Included in Net Loss:
Subsidiaries	0.2	0.0		0.0
Subsidiaries | Credit Losses
Changes in Net Unrealized (Losses) Gains on Investment Securities:
Unrealized Holding Gains (Losses) Arising During the Period Before Reclassification Adjustment	(0.5)	1.9		(2.0)
Changes in Net Unrealized (Losses) Gains on Investment Securities:
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax	0.2	(0.4)		0.4
Subsidiaries | No Credit Losses
Changes in Net Unrealized (Losses) Gains on Investment Securities:
Unrealized Holding Gains (Losses) Arising During the Period Before Reclassification Adjustment	235.0	(1,535.7)		(230.4)
Changes in Net Unrealized (Losses) Gains on Investment Securities:
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax	(49.5)	322.7		48.4
Parent Company
Condensed Statement of Income Captions [Line Items]
Net Loss	(272.3)	(286.6)		(123.7)
Reclassification Adjustment for Amounts Included in Net Loss:
Reclassification Adjustment for Amounts Included in Net Income	(0.1)	0.0		(10.6)
Unrecognized Postretirement Benefit Costs Arising During the Year	(7.4)	18.2		(9.5)
Amortization of Accumulated Unrecognized Pension Loss	(0.3)	0.0		0.0
Reclassification Adjustment for Postretirement Benefit Costs Arising During the Year:
Parent	66.8	(0.4)		0.1
Gains on Cash Flow Hedge	(0.2)	5.9		0.5
Other Comprehensive Income (Loss) Before Income Taxes	195.6	(143.7)		(66.3)
Reclassification Adjustment for Amounts Included in Net Loss:
Reclassification Adjustment for Amounts Included in Net Income	0.1	0.0		2.2
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax	1.3	(3.9)		2.5
Reclassification Adjustments for Amounts Included in Net Loss:
Subsidiaries	(14.0)	0.1		0.0
Changes in Gain on Cash Flow Hedges	(0.1)	(1.2)		(0.1)
Debt Extinguishment, Pension Settlement, and Other Charges	70.2	0.0		0.0
Changes in Gain on Cash Flow Hedges	0.2	(5.9)		(0.5)
Other Comprehensive Income Tax Benefit (Expense)	(41.5)	30.4		14.5
Other Comprehensive Income (Loss), Net of Taxes	154.1	(113.3)		(51.8)
Less: Total Comprehensive Loss attributable to Noncontrolling Interest	(0.2)	0.0		0.0
Comprehensive Loss attributable to Kemper Corporation	(118.0)	(399.9)		(175.5)
Parent Company | No Credit Losses
Changes in Net Unrealized (Losses) Gains on Investment Securities:
Unrealized Holding Gains (Losses) Arising During the Period Before Reclassification Adjustment	(0.6)	(2.6)		0.0
Changes in Net Unrealized (Losses) Gains on Investment Securities:
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax	$ 0.1	$ 0.5		$ 0.0

[1] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been recast to reflect application of the new guidance. See Note 2 to the Consolidated Financial Statements for additional information.