Schedule 2 - Parent Company Financial Statements - Statements of Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Statement of Income Captions [Line Items]
Net Income (Loss)	$ 312.5	$ (272.3)	$ (286.6)
Reclassification Adjustment for Postretirement Benefit Costs Arising During the Year:
Change in Discount Rate on Future Life Policyholder Benefits	278.0	(101.7)	1,380.7
Other Comprehensive Income (Loss) Before Income Taxes	71.3	195.6	(143.7)
Reclassification Adjustment for Postretirement Benefit Costs Arising During the Year:
Change in Discount Rate on Future Life Policyholder Benefits	58.3	(21.2)	289.9
Other Comprehensive Income Tax Expense (Benefit)	15.0	41.5	(30.4)
Other Comprehensive Income (Loss), Net of Taxes	56.3	154.1	(113.3)
Total Comprehensive Income (Loss)	368.8	(118.2)	(399.9)
Less: Total Comprehensive Loss attributable to Noncontrolling Interest	(5.3)	(0.2)	0.0
Comprehensive Income (Loss) attributable to Kemper Corporation	374.1	(118.0)	(399.9)
Subsidiaries
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:
Unrecognized Postretirement Benefit Costs Arising During the Year	0.5	0.1	1.1
Reclassification Adjustment for Postretirement Benefit Costs Arising During the Year:
Amortization of Accumulated Unrecognized Pension Loss	(0.3)	(0.3)	0.0
Unrecognized Gain (Loss) on Cash Flow Hedges Arising During the Year:	(6.3)	0.0	0.0
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:	1.8	1.0	(2.7)
Unrecognized Postretirement Benefit Costs Arising During the Year:	0.1	0.0	0.2
Reclassification Adjustment for Postretirement Benefit Costs Arising During the Year:
Subsidiaries	0.0	(0.2)	0.0
Unrecognized Gain (Loss) on Cash Flow Hedges Arising During the Year:	(0.9)	0.0	0.0
Subsidiaries | No Credit Losses
Changes in Net Unrealized Gains (Losses) on Investment Securities:
Unrealized Holding Gains (Losses) Arising During the Period Before Reclassification Adjustment	(210.5)	235.0	(1,535.7)
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:
Reclassification Adjustment for Amounts Included in Net Income	8.8	4.5	(12.8)
Changes in Net Unrealized (Losses) Gains on Investment Securities:
Changes in Net Unrealized (Losses) Gains on Investment Securities:	(44.2)	49.5	(322.7)
Subsidiaries | Credit Losses
Changes in Net Unrealized Gains (Losses) on Investment Securities:
Unrealized Holding Gains (Losses) Arising During the Period Before Reclassification Adjustment	(0.6)	(0.5)	1.9
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:
Reclassification Adjustment for Amounts Included in Net Income	(0.7)	0.0	0.0
Changes in Net Unrealized (Losses) Gains on Investment Securities:
Changes in Net Unrealized (Losses) Gains on Investment Securities:	(0.3)	(0.2)	0.4
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:	(0.3)	0.0	0.0
Parent Company
Condensed Statement of Income Captions [Line Items]
Net Income (Loss)	317.8	(272.3)	(286.6)
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:
Unrecognized Postretirement Benefit Costs Arising During the Year	1.3	(7.4)	18.2
Reclassification Adjustment for Postretirement Benefit Costs Arising During the Year:
Amortization of Accumulated Unrecognized Pension Loss	(2.8)	66.8	(0.4)
Reclassification Adjustment for Gain (Loss) on Cash Flow Hedges Arising During the Year:	(0.9)	0.2	(5.9)
Other Comprehensive Income (Loss) Before Income Taxes	71.3	195.6	(143.7)
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:	0.5	(0.1)	0.0
Unrecognized Postretirement Benefit Costs Arising During the Year:	0.3	(1.3)	3.9
Reclassification Adjustment for Postretirement Benefit Costs Arising During the Year:
Subsidiaries	(0.6)	14.0	(0.1)
Parent	0.2	0.1	1.2
Other Comprehensive Income Tax Expense (Benefit)	15.0	41.5	(30.4)
Other Comprehensive Income (Loss), Net of Taxes	56.3	154.1	(113.3)
Total Comprehensive Income (Loss)	374.1	(118.2)	(399.9)
Less: Total Comprehensive Loss attributable to Noncontrolling Interest	0.0	(0.2)	0.0
Comprehensive Income (Loss) attributable to Kemper Corporation	374.1	(118.0)	(399.9)
Parent Company | No Credit Losses
Changes in Net Unrealized Gains (Losses) on Investment Securities:
Unrealized Holding Gains (Losses) Arising During the Period Before Reclassification Adjustment	0.6	(0.6)	(2.6)
Reclassification Adjustment for Securities Having No Credit Losses Included in Net Loss:
Reclassification Adjustment for Amounts Included in Net Income	2.4	(0.1)	0.0
Changes in Net Unrealized (Losses) Gains on Investment Securities:
Changes in Net Unrealized (Losses) Gains on Investment Securities:	$ 0.1	$ (0.1)	$ (0.5)