Earnings per Common Share - Calculation of Weighted-Average Shares Excluded from Diluted EPS (Details) - Stock Compensation Plan - shares shares in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| 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 due to net loss | 0 | 1,478 | 1,481 |
| Weighted-average stock appreciation rights and stock awards excluded from diluted EPS due to the anti-dilutive effect calculated using the treasury stock method | 28 | 1 | 2 |
| Weighted-average stock appreciation rights and stock awards excluded from diluted EPS due to the anti-dilutive effect | 28 | 1,479 | 1,483 |