Earnings per Common Share - Antidilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average number of antidilutive potential common shares excluded from computation (in shares)	0	58,483	58,667
Series B Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average number of antidilutive potential common shares excluded from computation (in shares)	0	33,240	33,240
Common share warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average number of antidilutive potential common shares excluded from computation (in shares)	0	18,575	18,575
Employee stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average number of antidilutive potential common shares excluded from computation (in shares)	0	5,983	6,299
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average number of antidilutive potential common shares excluded from computation (in shares)	0	685	553