Segment Information - Net Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Net income	$ 468	$ 372	$ 741	$ 1,002
Preferred stock dividends	5	0	10	5
Net income available to common stockholders	463	372	731	997
Corporate
Segment Reporting Information [Line Items]
Net income	18	(43)	(73)	(43)
Commercial Lines
Segment Reporting Information [Line Items]
Net income	(66)	191	55	554
Personal Lines
Segment Reporting Information [Line Items]
Net income	371	62	469	158
Property & Casualty Other Operations
Segment Reporting Information [Line Items]
Net income	5	11	10	34
Group Benefits
Segment Reporting Information [Line Items]
Net income	101	113	205	231
Hartford Funds
Segment Reporting Information [Line Items]
Net income	$ 39	$ 38	$ 75	$ 68