Debt - Additional Information (Details) £ in Millions	1 Months Ended		12 Months Ended
	Jun. 17, 2019	Apr. 30, 2017	Dec. 31, 2019 USD ($)	Dec. 31, 2019 GBP (£)
Debt Instrument [Line Items]
Registration Payment Arrangement, Term	three
Debt Instrument, Payment Terms			The Company has the right to defer interest payments for up to a consecutive ten years without giving rise to an event of default. Deferred interest will continue to accrue and will accrue additional interest at the then applicable interest rate. If the Company defers interest payments, the Company generally may not make payments on or redeem or purchase any shares of its capital stock or any of its debt securities or guarantees that rank upon liquidation, dissolution or winding up equally with or junior to the debentures, subject to certain limited exceptions.
Line of Credit Facility, Description			The Company has a senior unsecured five-year revolving credit facility (“Credit Facility”) that provides up to $750 of unsecured credit through March 29, 2023. Revolving loans from the Credit Facility may be in multiple currencies. U.S. dollar loans will bear interest at a floating rate equivalent to an indexed rate depending on the type of borrowing and a basis point spread based on The Hartford's credit rating and will mature no later than March 29, 2023. Letters of credit issued from the Credit Facility bear a fee based on The Hartford's credit rating and expire no later than March 29, 2024. The Credit Facility requires the Company to maintain a minimum consolidated net worth, excluding AOCI, of $9 billion, limit the ratio of senior debt to capitalization, excluding AOCI, at 35% and meet other customary covenants. The Credit Facility is for general corporate purposes.
Letters of Credit Outstanding, Amount			$ 5,000,000
Commercial paper outstanding			0
Federal Home Loan Bank, Advances, Affordable Housing Program, Principal Outstanding			0
Bilateral Facility [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount			18,000,000
Debt Instrument, Face Amount			11
Debt Instrument, Unused Borrowing Capacity, Amount			1,000,000
Club Facility [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount			165,000,000	£ 60
Commercial Paper
Debt Instrument [Line Items]
Credit facility			$ 750,000,000
Senior Note Six Point Zero Percent Due in Two Thousand Nineteen [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.00%	6.00%
Senior Note Five Point Five Percent Due in Two Thousand Twenty [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			5.50%	5.50%
Senior Note Five Point One Two Five Percent Due in Two Thousand Twenty Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			5.125%	5.125%
Senior Note Two Point Eight Percent Due in Two Thousand Twenty Nine [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			2.80%	2.80%
Senior Note Five Point Nine Five Percent Due in Two Thousand Thirty Six [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			5.95%	5.95%
Senior Note Six Point Six Two Five Percent Due in Two Thousand Forty [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.625%	6.625%
Senior Note Six Point One Percent Due in Two Thousand Forty One [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.10%	6.10%
Senior Note Six Point Six Two Five Percent Due in Two Thousand Forty Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.625%	6.625%
Senior Note Four Point Three Percent Due in Two Thousand Fourty Three [Member] [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			4.30%	4.30%
Senior Note Four Point Four Due in Two Thousand Forty Eight [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			4.40%	4.40%
Senior Note Three Point Six Percent Due in Two Thousand Forty Nine [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			3.60%	3.60%
Junior Subordinated Notes Seven Point Eight Seventy Five Percent Due in Two Thousand Forty Two
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			7.875%	7.875%
LIBOR Plus Two Point One Two Five Percent Junior Subordinated Notes Due Two Thousand Sixty Seven | Interest Rate Subsequent to Call Date [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.125%	2.125%
Junior Subordinate Notes Eight Point One Two Five Note Due Two Thousand Sixty Eight
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			8.125%	8.125%
LIBOR Plus Five Point Five Nine Six Percent Junior Subordinated Notes Due Two Thousand Twenty Two [Member] [Domain] | Interest Rate Subsequent to Call Date [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			5.596%
Maximum | Hartford Fire Insurance Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Collateral Amount			$ 1,200,000,000
Maximum | Hartford Life and Accident Insurance Company [Member]
Debt Instrument [Line Items]
Debt Instrument, Collateral Amount			$ 600,000,000