Basis of Presentation - Schedule of Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic earnings per share calculation:
Net income	$ 52,398	$ 40,591	$ 47,856
Weighted-average basic shares outstanding	27,627,228	19,165,182	17,180,000
Basic earnings per share	$ 1.90	$ 2.12	$ 2.79
Diluted earnings per share:
Net income	$ 52,398	$ 40,591	$ 47,856
Weighted-average basic shares outstanding	27,627,228	19,165,182	17,180,000
Average diluted common shares outstanding	580,374	146,992	0
Weighted-average diluted shares outstanding	28,207,602	19,312,174	17,180,000
Diluted earnings per share	$ 1.86	$ 2.10	$ 2.79
Pro forma earnings per share:
Pro forma net income	$ 52,398	$ 39,422	$ 32,995
Weighted-average basic shares outstanding	27,627,228	19,165,182	17,180,000
Pro forma basic earnings per share	$ 1.90	$ 2.06	$ 1.92
Pro forma diluted earnings per share:
Pro forma net income	$ 52,398	$ 39,422	$ 32,995
Weighted-average diluted shares outstanding	28,207,602	19,312,174	17,180,000
Pro forma diluted earnings per share	$ 1.86	$ 2.04	$ 1.92