Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reconciliation of the component parts of earnings per share [Abstract]
Net income	$ 14,808	$ 10,947
Weighted average common shares (in shares)	96,353	95,879
Stock Options (in shares)	131	108
Weighted average common shares including potential dilutive shares (in shares)	96,484	95,987
Basic EPS (in dollars per share)	$ 0.154	$ 0.114
Diluted EPS (in dollars per share)	$ 0.153	$ 0.114
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of antidilutive stock options excluded from diluted earnings per share (in shares)	0	553