Earnings per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic earnings per share
Net income	$ 16,322	$ 14,216	$ 51,313	$ 29,818
Average common stock outstanding (in shares)	47,205,383	43,151,248	47,108,302	41,626,356
Net income per share (in dollars per share)	$ 0.35	$ 0.33	$ 1.09	$ 0.72
Diluted earnings per share
Net income	$ 16,322	$ 14,216	$ 51,313	$ 29,818
Average common stock outstanding (in shares)	47,205,383	43,151,248	47,108,302	41,626,356
Add: Dilutive effect of employee restricted stock and stock options (in shares)	823,947	640,860	794,791	671,780
Average shares outstanding - diluted (in shares)	48,029,330	43,792,108	47,903,093	42,298,136
Net income per share (in dollars per share)	$ 0.34	$ 0.32	$ 1.07	$ 0.70