Earnings per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Basic earnings per share
Net income	$ 23,253	$ 16,964	$ 45,958	$ 34,991
Average common shares outstanding (in shares)	51,446	47,165	51,403	47,059
Net income per share (in dollars per share)	$ 0.45	$ 0.36	$ 0.89	$ 0.74
Diluted earnings per share
Average common shares outstanding (in shares)	51,446	47,165	51,403	47,059
Add: Dilutive effect of employee restricted stock and stock options (in shares)	506	809	595	769
Average diluted shares outstanding (in shares)	51,952	47,974	51,998	47,828
Net income per share (in dollars per share)	$ 0.45	$ 0.35	$ 0.88	$ 0.73