Equity-based Compensation - Summary of Stock Option Activity (Details) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares
Outstanding at beginning of the period (in shares)	170,253	288,383	503,134
Exercised (in shares)	(43,573)	(114,307)	(209,205)
Canceled/Expired (in shares)	0	(3,823)	(5,546)
Outstanding at end of the period (in shares)	126,680	170,253	288,383
Exercisable (in shares)	126,680	170,253	284,929
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding at beginning of the period (in Dollars per share)	$ 21.99	$ 21.73	$ 18.18
Exercised (in Dollars per share)	18.87	21.33	13.13
Canceled/Expired (in Dollars per share)	0.00	22.24	24.21
Outstanding at end of the period (in Dollars per share)	23.06	21.99	21.73
Exercisable (in Dollars per share)	$ 23.06	$ 21.99	$ 21.78
Compensation not yet recognized stock options	$ 0
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, general term	7 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, general term	10 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Expense recorded	$ 0	$ 100,000	$ 100,000

General term of stock options

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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 options awarded to employees as compensation.

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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 number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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Number of options outstanding, including both vested and non-vested options.

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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Number of share options (or share units) exercised during the current period.

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