Segment Information - Net Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net income	$ 459	$ 535	$ 1,200	$ 1,537
Preferred stock dividends	6	11	16	16
Net income available to common stockholders	453	524	1,184	1,521
Corporate
Segment Reporting Information [Line Items]
Net income	(108)	(99)	(181)	(142)
Commercial Lines
Segment Reporting Information [Line Items]
Net income	323	336	378	890
Personal Lines
Segment Reporting Information [Line Items]
Net income	79	94	548	252
Property & Casualty Other Operations
Segment Reporting Information [Line Items]
Net income	2	18	12	52
Group Benefits
Segment Reporting Information [Line Items]
Net income	119	146	324	377
Hartford Funds
Segment Reporting Information [Line Items]
Net income	$ 44	$ 40	$ 119	$ 108