Accrued Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs	$ 11	$ 0
Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring	(14)
Employee Severance | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring	(6)
Information Technology | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring	(2)
Professional fees and other expenses | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring	(6)
Other Operating Income (Expense) [Member] | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs	11
Other Operating Income (Expense) [Member] | Employee Severance | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs	0
Other Operating Income (Expense) [Member] | Information Technology | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs	2
Other Operating Income (Expense) [Member] | Professional fees and other expenses | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Restructuring and other costs	9
Other liabilities | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Beginning Balance	54
Restructuring Reserve, Ending Balance	51
Other liabilities | Employee Severance | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Beginning Balance	54
Restructuring Reserve, Ending Balance	48
Other liabilities | Information Technology | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Beginning Balance	0
Restructuring Reserve, Ending Balance	0
Other liabilities | Professional fees and other expenses | Hartford Next Program
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Beginning Balance	0
Restructuring Reserve, Ending Balance	$ 3