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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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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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Intrinsic value of equity-based compensation awards vested. Excludes stock and unit options.

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Share and Incentive-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Oct. 31, 2016
Share and Incentive Based Compensation Arrangement
Shares authorized for issuance			4.6
Performance Share Units
Share and Incentive Based Compensation Arrangement
Aggregate intrinsic value of awards		$ 1.7
Unvested awards (in shares)	0.1
Restricted Stock
Share and Incentive Based Compensation Arrangement
Unvested awards (in shares)	0.4
Weighted average grant date fair value	$ 16.07
Compensation yet not yet recognized	$ 3.9
Compensation yet not yet recognized period	2 years 1 month 6 days
Restricted Stock \| Minimum
Share and Incentive Based Compensation Arrangement
Vesting period	1 year
Restricted Stock \| Maximum
Share and Incentive Based Compensation Arrangement
Vesting period	3 years