Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reconciliation of basic to diluted weighted average shares outstanding
Net income	$ 6,950	$ 11,508	$ 16,341	$ 28,904
Net weighted average common shares outstanding, basic (in shares)	87,736,000	87,830,000	87,660,000	87,551,000
Dilutive effect of stock options (in shares)	272,000	1,146,000	293,000	1,268,000
Dilutive effect of restricted stock awards and units (in shares)	225,000	191,000	192,000	179,000
Weighted average common shares outstanding - diluted	88,233,000	89,167,000	88,145,000	88,998,000
Basic income per common share:
Income per common share - Basic	$ 0.08	$ 0.13	$ 0.19	$ 0.33
Diluted income per common share
Income per common share - Diluted	$ 0.08	$ 0.13	$ 0.19	$ 0.32
Employee And Directors Stock Options [Member]
Diluted income per common share
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	2,251,303	1,249,399	2,395,158	1,375,604
Restricted Stock Units R S U [Member]
Diluted income per common share
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	2,367	178,421	79,947	106,194