Segment Information - Non-insurance Revenue from Customers (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]
Insurance Commissions and Fees	$ 298	$ 326	$ 618	$ 640
Other revenues	88	32	105	85
Non-insurance revenues with customers	319	354	660	694
Installment billing fees [Member] | Operating Segments [Member] | Commercial Lines
Segment Reporting Information [Line Items]
Insurance Commissions and Fees	5	9	13	18
Installment billing fees [Member] | Operating Segments [Member] | Personal Lines
Segment Reporting Information [Line Items]
Insurance Commissions and Fees	9	10	18	19
Insurance servicing revenues | Operating Segments [Member] | Personal Lines
Segment Reporting Information [Line Items]
Other revenues	21	23	40	42
Administrative services | Operating Segments [Member] | Group Benefits
Segment Reporting Information [Line Items]
Insurance Commissions and Fees	45	45	88	90
Advisor, distribution and other management fees | Operating Segments [Member] | Hartford Funds
Segment Reporting Information [Line Items]
Insurance Commissions and Fees	207	228	431	446
Other fees | Operating Segments [Member] | Hartford Funds
Segment Reporting Information [Line Items]
Insurance Commissions and Fees	20	22	43	43
Investment management and other fees | Corporate
Segment Reporting Information [Line Items]
Insurance Commissions and Fees	12	11	25	24
Transition service revenues | Corporate
Segment Reporting Information [Line Items]
Other revenues	$ 0	$ 6	$ 2	$ 12