Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reconciliation of the component parts of earnings per share [Abstract]
Net income	$ 10,930	$ 10,616	$ 31,803	$ 32,058
Weighted average common shares (in shares)	95,603	95,149	95,486	95,051
Stock Options (in shares)	119	85	86	116
Weighted average common shares including potential dilutive shares (in shares)	95,722	95,234	95,572	95,167
Basic EPS (in dollars per share)	$ 0.114	$ 0.112	$ 0.333	$ 0.337
Diluted EPS (in dollars per share)	$ 0.114	$ 0.111	$ 0.333	$ 0.337
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)	1,600	1,400	1,600	1,400