Equity-Based Compensation - Summary of Activity Related to Stock Options (Details) - Stock Options - $ / shares	1 Months Ended	9 Months Ended
Apr. 30, 2014	Sep. 30, 2018	Sep. 30, 2017
Number Outstanding
Outstanding at January 1,		2,436,232	2,822,728
Grants	3,501,881
Exercises		(348,280)	(256,270)
Forfeitures or expirations		(64,785)	(81,019)
Outstanding at September 30,		2,023,167	2,485,439
Weighted-Average Exercise Price Per Share
Outstanding at January 1,		$ 17.95	$ 17.95
Exercises		17.95	17.95
Forfeitures or expirations		17.95	17.95
Outstanding at September 30,		$ 17.95	$ 17.95

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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Gross number of share options (or share units) granted during the period.

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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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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