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Equity-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2013	May 04, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market price of common stock, per share	$ 35.59
Unrecognized compensation cost	$ 8.3
Weighted average cost recognition period, in years	1 year 11 months 1 day
Accrued equity based compensation	$ 38.4	$ 48.0
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Typical vesting period, in years	4 years
Performance stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Typical vesting period, in years	3 years
Shares awarded (in shares)	135,929	108,748	0
Award performance period	1 year
Forfeited in period (in shares)	57,788
Performance stock units outstanding (in shares)	235,485	480,462
Percent of targeted performance stock units earned	200.00%
Units vested (in shares)	256,000
Number of days trailing for closing price				90 days
2018 Plan | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized					1,000,000
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance under the Plan	946,000
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance under the Plan	73,000
Non-Employee Directors Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance under the Plan	60,000
Non Current Liabilities
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued equity based compensation	$ 23.6	$ 29.3

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Percentage of performance stock units earned during performance period based on the terms of the performance stock unit award.

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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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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 equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting 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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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 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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