Earnings per Share - Reconciliation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Numerator for basic and diluted EPS — net income (loss)	$ (15,386)	$ 6,368
Denominator for basic EPS — weighted average number of shares (shares)	23,955,714	29,754,957.000
Add — dilutive effect of:
Restricted stock units	0	444,000
Denominator for diluted EPS — weighted average number of shares and dilutive potential shares (shares)	23,955,714	30,198,797.000
Earnings per share:
Basic (usd per share)	$ (0.64)	$ 0.21
Diluted (usd per share)	$ (0.64)	$ 0.21
Antidilutive securities excluded from EPS (shares)	1,994,492	1,255,997
Cogent Partners, LP
Earnings per share:
Incremental common shares attributable to dilutive effect of contingently issuable shares (shares)	334,048
Unamortized Restricted Stock Units [Member]
Add — dilutive effect of:
Restricted stock units	657,255
Earnings per share:
Antidilutive securities excluded from EPS (shares)	4,053,441

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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