Earnings Per Common Share - Reconciliation of Basic and Diluted Net Income Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income per consolidated statements of income	$ 32,326	$ 47,136	$ 47,974	$ 38,825	$ 14,691	$ 32,577	$ 28,968	$ 26,117	$ 166,261	$ 102,353	$ 65,774
Net income allocated to participating securities									(197)
Net income allocated to common stock									$ 166,064	$ 102,353	$ 65,774
Weighted average common shares outstanding (Basic)									83,562,109	81,072,945	75,000,000
Weighted average dilutive restricted stock units									813,180	532,070	294,600
Weighted average common shares outstanding (Diluted)									84,375,289	81,605,015	75,294,600
Earnings per common share (Basic)	$ 0.39	$ 0.56	$ 0.57	$ 0.46	$ 0.18	$ 0.39	$ 0.35	$ 0.35	$ 1.99	$ 1.26	$ 0.88
Earnings per common share (Diluted)	$ 0.39	$ 0.56	$ 0.57	$ 0.46	$ 0.17	$ 0.39	$ 0.35	$ 0.35	$ 1.97	$ 1.25	$ 0.87