Shareholders' Equity - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	May 06, 2020	Aug. 06, 2014
Schedule of Capitalization, Equity [Line Items]
Preferred stock, shares authorized (in shares)	20,000,000
Preferred stock, par value (in dollars per share)	$ 0.10
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, shares issued (in shares)	0
Preferred stock, shares outstanding (in shares)		0
Common stock, shares outstanding (in shares)	63,912,762	63,684,628
Stock Repurchase Program, Additional Authorized Amount				$ 200,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 171,600,000		$ 333,300,000		$ 133,300,000
Stock repurchased and retired during period (in shares)		2,085,000	1,617,000
Stock Repurchased and Retired During Period, Value		$ 161,700,000	$ 110,400,000
Share-based compensation expense	$ 17,700,000	28,000,000	24,900,000
Percentage of authorized control Level RBC	200.00%
Dividends paid	$ 79,700,000	$ 80,600,000	$ 78,900,000
Amount available for dividend payment	800,000,000
Common Stock
Schedule of Capitalization, Equity [Line Items]
Average cost per share (in dollars per share)		$ 77.58	$ 68.29
Kemper's Insurance Subsidiaries
Schedule of Capitalization, Equity [Line Items]
Cash dividends paid by Kemper's Insurance Subsidiaries to Kemper	311,700,000
Amount available for dividend payments	108,900,000
Amount of restricted net assets for consolidated and unconsolidated subsidiaries	3,500,000,000
Life & Health Insurance | Kemper's Insurance Subsidiaries
Schedule of Capitalization, Equity [Line Items]
Statutory capital and surplus	265,200,000	$ 446,000,000
Statutory net income	174,400,000	(12,400,000)	$ 60,700,000
Statutory capital and surplus required	50,000,000
Property & Casualty Insurance Subsidiaries | Kemper's Insurance Subsidiaries
Schedule of Capitalization, Equity [Line Items]
Statutory capital and surplus	1,600,000,000	1,500,000,000
Statutory net income	(226,700,000)	$ (206,900,000)	$ 361,600,000
Statutory capital and surplus required	$ 665,700,000
Employee Stock Purchase Plan | Employee Stock
Schedule of Capitalization, Equity [Line Items]
Shares issued under employee stock purchase plan (in shares)	102,000	79,000	61,000
Price per share (in dollars per share)	$ 40.83	$ 58.08	$ 61.57
Share-based compensation expense	$ 700,000	$ 800,000	$ 700,000