Equity-based Compensation - Summary of Stock Award Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Awards
Stock Awards - Outstanding (in shares)	1,501,021
Stock Awards - Outstanding (in shares)		1,501,021
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Outstanding (in Dollars per share)	$ 20.58
Weighted Average Award Date Fair Value - Outstanding (in Dollars per share)	$ 21.53	$ 20.58
Restricted Stock and Restricted Stock Units
Stock Awards
Stock Awards - Outstanding (in shares)	1,501,021	1,275,707	767,540
Stock Awards - Outstanding (in shares)	1,428,878	1,501,021	1,275,707
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Outstanding (in Dollars per share)	$ 20.58	$ 20.54	$ 21.93
Weighted Average Award Date Fair Value - Outstanding (in Dollars per share)		$ 20.58	$ 20.54
Expense associated with stock awards	$ 10.1	$ 8.3	$ 6.8
Unrecognized pre-tax expense	$ 11.8
Remaining period for recognition	1 year 8 months 13 days
Restricted Stock
Stock Awards
Stock Awards - Distributed (in shares)	(179,169)	(162,554)	(90,607)
Stock Awards - Forfeited (in shares)	(1,084)	(22,045)	(54,045)
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Distributed (in Dollars per share)	$ 22.44	$ 23.49	$ 19.25
Weighted Average Award Date Fair Value - Forfeited (in Dollars per share)	$ 23.01	$ 23.34	$ 23.40
Restricted Stock Units (RSUs)
Stock Awards
Stock Awards - Awarded (in shares)	257,532	335,026	422,141
Stock Awards - Distributed (in shares)	(95,510)	(23,739)	(12,646)
Stock Awards - Forfeited (in shares)	(81,626)	(71,992)	(27,360)
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Awarded (in Dollars per share)	$ 23.06	$ 18.43	$ 17.37
Weighted Average Award Date Fair Value - Distributed (in Dollars per share)	20.71	20.73	19.62
Weighted Average Award Date Fair Value - Forfeited (in Dollars per share)	$ 20.36	$ 17.60	$ 18.79
Performances Stock Units
Stock Awards
Stock Awards - Awarded (in shares)	213,436	245,586	297,164
Stock Awards - Distributed (in shares)	(49,672)	0	0
Stock Awards - Forfeited (in shares)	(136,050)	(74,968)	(26,480)
Weighted Average Award Date Fair Value
Weighted Average Award Date Fair Value - Awarded (in Dollars per share)	$ 28.18	$ 25.69	$ 21.55
Weighted Average Award Date Fair Value - Distributed (in Dollars per share)	21.95	0.00	0.00
Weighted Average Award Date Fair Value - Forfeited (in Dollars per share)	$ 24.29	$ 22.64	$ 22.42
2016 Employee Plan
Weighted Average Award Date Fair Value
Common stock available for equity-based compensation awards (in dollars per share)	1,501,962
2016 Employee Plan \| Restricted Stock and Restricted Stock Units
Stock Awards
Stock Awards - Outstanding (in shares)	448,225

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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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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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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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