Earnings Per Share - Components of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 320	$ 15,103	$ 9,865	$ 3,963	$ 2,976	$ 2,567	$ 1,873	$ 2,738	$ 29,251	$ 10,154	$ 11,768
Less: dividends paid to participating securities									0	0	(18,987)
Less: income allocated to participating securities									(13)	(12)	0
Net income / (loss) attributable to common stockholders									$ 29,238	$ 10,142	$ (7,219)
Weighted average common shares outstanding — basic (in shares)									46,682,141	45,716,757	24,108,362
Dilutive effect of stock options, restricted stock units and restricted stock awards (in shares)									2,471,807	2,158,765	0
Weighted average common shares outstanding — diluted (in shares)									49,153,948	47,875,522	24,108,362
Net income / (loss) per share:
Basic (USD per share)	$ 0.01	$ 0.32	$ 0.21	$ 0.09	$ 0.06	$ 0.06	$ 0.04	$ 0.06	$ 0.63	$ 0.22	$ (0.30)
Diluted (USD per share)	$ 0.01	$ 0.31	$ 0.20	$ 0.08	$ 0.06	$ 0.05	$ 0.04	$ 0.06	$ 0.59	$ 0.21	$ (0.30)