Common Stock Redeemed For Payment of Stock Option Exercises, Aggregate Value

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Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Compensation Plans

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

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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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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Percentage of vesting of award 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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Number of shares issued during the period related to Restricted Stock Awards, net of any shares forfeited.

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Stock-Based Compensation - Narrative (Details)	12 Months Ended
Stock-Based Compensation - Narrative (Details)	Dec. 31, 2019 USD ($) plan shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation plans \| plan	2
Options expiration period	10 years
Stock option awards granted \| shares	0	0
Stock compensation expense	$ 8,000,000.0	$ 5,600,000	$ 3,800,000
Intrinsic value of fully-vested stock options outstanding	5,800,000
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense		0
Tax benefits from stock-based compensation		0
Total intrinsic value of options exercised	4,900,000	4,900,000	6,300,000
Proceeds from Stock Options Exercised	1,000,000.0	1,800,000	2,400,000
Common Stock Redeemed For Payment of Stock Option Exercises, Aggregate Value	2,000,000.0	1,600,000	2,800,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense		5,600,000	3,300,000
Tax benefits from stock-based compensation	$ 400,000	$ 200,000	$ 600,000
Stock issued during period, shares, restricted stock award \| shares	230,922
Unrecognized compensation cost related to nonvested restricted stock awards	$ 8,100,000
Unrecognized compensation cost related to nonvested restricted stock to be recognized over weighted average period (in years)	1 year 1 month 6 days
Restricted Stock [Member] \| Upon Achievement of Performance Goals
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, restricted stock award \| shares	72,926
Restricted Stock [Member] \| Upon Achievement of Defined Return on Equity Performance Goals
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, restricted stock award \| shares	36,463
Restricted Stock [Member] \| Upon Achievement of Defined Total Return to Shareholder Goals
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, restricted stock award \| shares	36,463
Restricted Stock [Member] \| Upon One-Third Annual Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, restricted stock award \| shares	139,661
Restricted Stock [Member] \| First Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage		33.33%
Restricted Stock [Member] \| Second Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage		33.33%
Restricted Stock [Member] \| Third Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage		33.33%
2006 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant \| shares	1,492,762