Earnings Per Share - Securities Excluded from the Computation of Diluted Earnings (Loss) Per Common Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded in computation of diluted earning per share (in shares)	382	165	357	147
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded in computation of diluted earning per share (in shares)	204	0	172	29
Performance-based warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded in computation of diluted earning per share (in shares)	0	0	0	0