Earnings (Loss) Per Share - Narrative (Details) - shares	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential antidilutive securities excluded from future computations of earnings per share, amount (in shares)	1,981,879	2,364,018	1,973,753	2,281,805

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.

No definition available.

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