Share-based Compensation Arrangements by Share-based Payment Award, Target Performance Ratio

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Stock-based Compensation Arrangement by Share-based Payment Award, Performance Period

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Subsidiary Stock

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The weighted average per share fair value of the discount under the ESPP plan.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Aggregate cash paid by the entity during the period to settle equity instruments granted under equity-based payment arrangements.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Discount rate from fair value on offering date that participants pay for shares.

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Discount rate from fair value on purchase date that participants pay for shares.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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Number of shares issued under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Stock Compensation Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost related to non-vested awards not yet recognized		$ 68
Weighted average period of compensation cost recognized		2 years
Share-based Payment Arrangement, Plan Modification, Incremental Cost	$ 0
Maximum number of shares that may be issued (in shares)		15,400,000
Shares available for future issuance (in shares)		3,743,847
Award vesting period		3 years
Weighted average grant-date fair value of options granted during period (in shares)		$ 12.97	$ 11.71	$ 14.04
Total intrinsic value of options exercised during period		$ 2	$ 16	$ 14
Share-based Payment Arrangement, Cash Used to Settle Award		0	0	0
Stock-based compensation plans expense		$ 116	$ 125	$ 130
Discount rate for employee stock purchase plan		5.00%
Shares sold during period (in shares)		340,653	213,472	219,661
Weighted average per share fair value of discount (in USD per share)		$ 1.99	$ 2.82	$ 2.56
Discount rate from market price per share, purchase date		5.00%
Subsidiary Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation plans expense		$ 11	$ 11	$ 9
Subsidiary stock repurchased		$ 10
Employee Stock Option Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term		3 years	3 years	3 years
Stock-based Compensation Arrangement by Share-based Payment Award, Performance Period		3 years
Weighted average grant-date fair value (in USD per share)		$ 55.62	$ 54.07	$ 50.26
Total fair value of shares vested during period		$ 73	$ 102	$ 114
Performance Shares \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance ratio		200.00%
Performance Shares \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance ratio		0.00%
Performance Shares One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Performance Shares Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		5 years
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value (in USD per share)		$ 54.64	$ 50.49	$ 53.11
The Hartford 2020 Incentive Stock Plan (ISOP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term		10 years
Maximum number of shares that may be issued (in shares)		11,250,000
Shares available for future issuance (in shares)		11,735,111
The Hartford 2020 Incentive Stock Plan (ISOP) [Member] \| Employee Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term		10 years
The Hartford 2020 Incentive Stock Plan (ISOP) [Member] \| Employee Stock Option One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Service period		1 year
The Hartford 2020 Incentive Stock Plan (ISOP) [Member] \| Restricted Stock Units One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
The Hartford 2020 Incentive Stock Plan (ISOP) [Member] \| Restricted Stock Units Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term		5 years
The Hartford 2020 Incentive Stock Plan (ISOP) [Member] \| Restricted Stock Units \| Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		1 year
The Hartford 2020 Incentive Stock Plan (ISOP) [Member] \| Restricted Stock Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years