Earnings per Common Share - Calculation of Weighted-Average Shares Excluded from Diluted EPS (Details) - shares shares in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock appreciation rights and stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average stock appreciation rights and stock awards excluded from diluted EPS due to the anti-dilutive effect calculated using the treasury stock method	1	2	1	6

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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