Equity-based Compensation - Summary of Stock Award Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Outstanding (in Dollars per share)	$ 21.53
Weighted Average Award Date Fair Value - Outstanding (in Dollars per share)	$ 23.26	$ 21.53
Restricted Stock and Restricted Stock Units
Stock Awards
Stock Awards - Outstanding (in shares)	1,428,878	1,501,021	1,275,707
Stock Awards - Outstanding (in shares)	1,143,205	1,428,878	1,501,021
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Outstanding (in Dollars per share)	$ 21.53	$ 20.58	$ 20.54
Weighted Average Award Date Fair Value - Outstanding (in Dollars per share)		$ 21.53	$ 20.58
Expense associated with stock awards	$ 6.8	$ 9.0	$ 9.1
Unrecognized pre-tax expense	$ 9.9
Remaining period for recognition	2 years 4 months 28 days
Restricted Stock
Stock Awards
Stock Awards - Distributed (in shares)	0	(179,169)	(162,554)
Stock Awards - Forfeited (in shares)	0	(1,084)	(22,045)
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Distributed (in Dollars per share)		$ 22.44	$ 23.49
Weighted Average Award Date Fair Value - Forfeited (in Dollars per share)	$ 0.00	$ 23.01	$ 23.34
Restricted Stock Units (RSUs)
Stock Awards
Stock Awards - Awarded (in shares)	281,567	257,532	335,026
Stock Awards - Distributed (in shares)	(312,182)	(95,510)	(23,739)
Stock Awards - Forfeited (in shares)	(90,896)	(81,626)	(71,992)
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Awarded (in Dollars per share)	$ 24.13	$ 23.06	$ 18.43
Weighted Average Award Date Fair Value - Distributed (in Dollars per share)	17.47	20.71	20.73
Weighted Average Award Date Fair Value - Forfeited (in Dollars per share)	$ 21.79	$ 20.36	$ 17.60
Performances Stock Units
Stock Awards
Stock Awards - Awarded (in shares)	219,943	213,436	245,586
Stock Awards - Distributed (in shares)	(296,909)	(49,672)	0
Stock Awards - Forfeited (in shares)	(87,196)	(136,050)	(74,968)
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Awarded (in Dollars per share)	$ 23.25	$ 28.18	$ 25.69
Weighted Average Award Date Fair Value - Distributed (in Dollars per share)	21.55	21.95	0.00
Weighted Average Award Date Fair Value - Forfeited (in Dollars per share)	$ 25.95	$ 24.29	$ 22.64

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

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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 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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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 number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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