Earnings per Common Share - Antidilutive Securities (Details) - shares shares in Thousands	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 [Line Items]
Weighted-average number of antidilutive potential common shares excluded from computation (in shares)	0	45,129	0	44,149
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	0	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	5,196	0	4,171
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	6,014	0	6,116
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	679	0	622