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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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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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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The number of grants made 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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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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No definition available.

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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 number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Number of shares related to Restricted Stock Award forfeited during the period.

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Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Feb. 28, 2019	Jan. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share awards authorized (in shares)				3,000,000
Number of shares were available for grant under two plans (in shares)	1,600,000
Shares surrendered to the Company (in shares)	70,068
Numbers of shares surrendered (in shares)	1,637
Stock-based employee compensation	$ 3.4	$ 3.4
Unrecognized compensation cost	$ 9.9
Remaining vesting period over which cost expected to be recognized	3 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised	$ 6.9	1.8
Tax benefit for impact of share based compensation	$ 1.0	$ 0.2
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock granted to directors (in shares)	4,257		3,510
Long Term Incentive Plan 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share awards authorized (in shares)					1,500,000
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based employee compensation	$ 0.3		$ 0.2