Earnings Per Share - Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Diluted earnings per share
Net income available for common stockholders, net of dividends and undistributed earnings allocated to participating securities	$ 1,613	$ 32,171	$ 20,887
Weighted average shares of common stock outstanding
Issued and outstanding	62,579,147	38,539,091	34,964,312
Weighted average number of shares of common stock outstanding	62,579,147	38,539,091	35,339,585
Diluted Earnings per share	$ 0.03	$ 0.83	$ 0.59
Anti-dilutive shares excluded from computation of EPS	1,740,630	743,096	0
Class A
Weighted average shares of common stock outstanding
Issued and outstanding	62,579,147	38,539,091	34,964,312
2015 Management Incentive Plan | Class A
Weighted average shares of common stock outstanding
Issuable pursuant to 2015 Management Incentive Plan			375,273