Earnings per Share - Reconciliation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Numerator for basic and diluted EPS — net income (loss)									$ 10,978	$ 39,222	$ (26,651)
Denominator for basic EPS — weighted average number of shares (shares)									24,024,674	26,813,285	32,074,894
Add — dilutive effect of:
Restricted stock units and Cogent Earnout shares									247,000	825,000	0
Denominator for diluted EPS — weighted average number of shares and dilutive potential shares (shares)									24,272,479	27,637,720	32,074,894
Earnings (loss) per share:
Basic (usd per share)	$ 1.05	$ 0.63	$ (0.53)	$ (0.64)	$ 0.46	$ 0.45	$ 0.39	$ 0.21	$ 0.46	$ 1.46	$ (0.83)
Diluted (usd per share)	$ 1.05	$ 0.63	$ (0.53)	$ (0.64)	$ 0.45	$ 0.43	$ 0.38	$ 0.21	$ 0.45	$ 1.42	$ (0.83)