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- Definition

Percentage of Stock-based Awards Possible to be Earned

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- Definition

Total Duration of the Stock Incentive Plan

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- Definition

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

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- Definition

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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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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- Definition

Amount of cash inflow from issuance of shares under share-based payment arrangement. Includes, but is not limited to, option exercised.

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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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- 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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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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- Definition

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

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- Definition

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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- Definition

Gross number of share options (or share units) granted during the period.

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- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Cash Received Under Share-based Payment Arrangements	$ 4.4	$ 6.1	$ 4.6
Fair Value of Options Vested	$ 0.0	$ 0.0	$ 0.0
Stock Incentive Plan 2017
Share-based Compensation Arrangement by Share-based Payment Award
Number of Shares Authorized	17,000,000
Number of Shares for Each Full Value Award	1.76
Total Duration of the Stock Incentive Plan	8 years
Award Vesting Period	3 years
Number of Shares Available for Grant	10,100,000
Stock Incentive Plan 2012
Share-based Compensation Arrangement by Share-based Payment Award
Number of Shares Authorized	20,000,000
Number of Shares for Each Full Value Award	1.76
Total Duration of the Stock Incentive Plan	8 years
Award Vesting Period	3 years
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award
Award Vesting Period	3 years
Weighted Average Grant Date Fair Value of Shares Granted	$ 23.49	$ 41.57	$ 44.19
Compensation Cost Not yet Recognized	$ 6.5
Period for Recognition of Compensation Cost Not Yet Recognized	1 year 7 months 6 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Weighted Average Grant Date Fair Value of Shares Granted	$ 22.71	$ 37.07	$ 47.76
Compensation Cost Not yet Recognized	$ 21.2
Period for Recognition of Compensation Cost Not Yet Recognized	10 months 24 days
Fair Value of Awards Vested During the Period	$ 25.1	$ 19.5	$ 18.1
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Stock Option Compensation Not yet Recognized	$ 0.0
Options Granted	0	0	0
Stock Success Units (SSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Award Vesting Period	6 years
Weighted Average Grant Date Fair Value of Shares Granted	$ 18.78
Compensation Cost Not yet Recognized	$ 5.7
Period for Recognition of Compensation Cost Not Yet Recognized	2 years 10 months 24 days
Fair Value of Awards Vested During the Period	$ 0.0
Cash Settled RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Weighted Average Grant Date Fair Value of Shares Granted	$ 22.94
Compensation Cost Not yet Recognized	$ 1.1
Period for Recognition of Compensation Cost Not Yet Recognized	1 year 1 month 6 days
Fair Value of Awards Vested During the Period	$ 0.0
Minimum \| Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of Stock-based Awards Possible to be Earned	40.00%
Minimum \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Award Vesting Period	1 year
Minimum \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award Vesting Period	1 year
Minimum \| Cash Settled RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Award Vesting Period	1 year
Maximum \| Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award
Percentage of Stock-based Awards Possible to be Earned	180.00%
Maximum \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Award Vesting Period	3 years
Maximum \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Award Vesting Period	3 years
Maximum \| Cash Settled RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Award Vesting Period	3 years