Earnings Per Share - Computation of Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Net loss per common share
Net income (loss)	$ 8,058	$ 450	$ (4,712)	$ (9,700)	$ 8,508	$ (14,412)
Weighted-average shares - basic (in shares)	34,395,266		33,397,709		34,247,977	33,338,243
Weighted-average shares - diluted (in shares)	35,091,906		33,397,709		35,089,740	33,338,243
Earnings (loss) per share - basic (in dollars per share)	$ 0.23		$ (0.14)		$ 0.25	$ (0.43)
Earnings (loss) per share - diluted (in dollars per share)	$ 0.23		$ (0.14)		$ 0.24	$ (0.43)
Stock options
Net loss per common share
Effect of dilutive securities	432,688				491,985
Restricted stock units
Net loss per common share
Effect of dilutive securities	212,221				262,849
Performance share units
Net loss per common share
Effect of dilutive securities	8,796				8,459
Employee Stock Purchase Program
Net loss per common share
Effect of dilutive securities	22,822				31,608
Warrants
Net loss per common share
Effect of dilutive securities	20,113				46,862