Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful receivables	$ 4,581	$ 3,932
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	158,986	155,911
Other intangible assets, accumulated amortization	$ 15,289	$ 15,186
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, par value	$ 0.02	$ 0.02
Common stock, shares issued	26,608,958	26,574,031
Treasury stock, shares	10,566,295	10,557,342