Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Condensed Consolidated Balance Sheets [Abstract]
Accounts receivable, reserves	$ 3,324	$ 2,632
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	100,805,000	100,160,000
Deferred stock units, outstanding	122,000	119,000
Treasury stock, shares	48,835,000	45,652,000