Earnings per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basic earnings per share
Net income	$ 22,705	$ 18,027
Average common shares outstanding (in shares)	51,359	46,952
Net income per share (in dollars per share)	$ 0.44	$ 0.38
Diluted earnings per share
Average common shares outstanding (in shares)	51,359	46,952
Add: Dilutive effect of employee restricted stock and stock options (in shares)	680	736
Average diluted shares outstanding (in shares)	52,039	47,688
Net income per share (in dollars per share)	$ 0.44	$ 0.38