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Earnings Per Share - Additional Information (Details) - shares
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Antidilutive securities excluded from computation of earnings per share, amount 0 0 12,415 0
Performance Shares | Initial Performance Vesting Period        
Share-based compensation arrangement by share-based payment award, award vesting period     2 years