Segment Information - Net Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Net income	$ 753	$ 535
Net income available to common stockholders	748	530
Corporate
Segment Reporting Information [Line Items]
Net income	(15)	(24)
Commercial Lines | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income	573	421
Personal Lines | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income	34	(1)
Property & Casualty Other Operations | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income	8	6
Group Benefits | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income	108	92
Hartford Funds | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net income	$ 45	$ 41