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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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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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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- Definition

Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the 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 which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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- Definition

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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- Definition

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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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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Number of share instruments newly issued under a share-based compensation plan.

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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	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost related to non-vested awards not yet recognized	$ 64
Weighted average period of compensation cost recognized	1 year 10 months 24 days
Maximum number of shares that may be issued (in shares)	15,400,000
Shares available for future issuance (in shares)	4,297,972
Award vesting period	3 years
Weighted average grant-date fair value of options granted during period (in shares)	$ 14.04	$ 12.38	$ 12.14
Total intrinsic value of options exercised during period	$ 14	$ 8	$ 1
Employee Service Share-based Compensation, Cash Flow Effect, Cash Used to Settle Awards		0	0
Stock-based compensation plans expense	$ 130	$ 116	$ 81
Discount rate for employee stock purchase plan	5.00%
Shares sold during period (in shares)	219,661	204,533	222,113
Weighted average per share fair value of discount (in USD per share)	$ 2.56	$ 2.63	$ 2.26
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	$ 9	$ 9	$ 7
Subsidiary stock repurchased	$ 4
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)	$ 50.26	$ 48.89	$ 41.50
Total fair value of shares vested during period	$ 114	$ 94	$ 128
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)	$ 53.11	$ 48.90	$ 42.87
The Hartford 2014 Incentive Stock Plan (ISOP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term	10 years
Maximum number of shares that may be issued (in shares)	12,000,000
Shares available for future issuance (in shares)	7,294,481
The Hartford 2014 Incentive Stock Plan (ISOP) \| Employee Stock Option \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term	10 years
The Hartford 2014 Incentive Stock Plan (ISOP) \| 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 2014 Incentive Stock Plan (ISOP) \| Restricted Stock Units One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
The Hartford 2014 Incentive Stock Plan (ISOP) \| Restricted Stock Units Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term	5 years
The Hartford 2014 Incentive Stock Plan (ISOP) \| Restricted Stock Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
The Hartford 2014 Incentive Stock Plan (ISOP) \| Restricted Stock Units \| Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year