Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reconciliation of basic to diluted weighted average shares outstanding
Net income	$ 6,038	$ 10,420	$ 9,391	$ 17,396
Net weighted average common shares outstanding, basic (in shares)	87,691,000	87,674,000	87,564,000	87,408,000
Dilutive effect of stock options (in shares)	230,000	1,200,000	301,000	1,336,000
Dilutive effect of restricted stock awards and units (in shares)	171,000	149,000	168,000	175,000
Weighted average common shares outstanding, diluted (in shares)	88,092,000	89,023,000	88,033,000	88,919,000
Basic income per common share:
Income per common share - Basic	$ 0.07	$ 0.12	$ 0.11	$ 0.20
Diluted income per share:
Income per common share - Diluted	$ 0.07	$ 0.12	$ 0.11	$ 0.20
Employee And Directors Stock Options [Member]
Anti-dilutive securities
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	2,562,229	1,413,369	2,443,375	1,375,346
Restricted Stock Units R S U [Member]
Anti-dilutive securities
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)	189,278	9,085	52,171	102,847