Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2011	Dec. 31, 2010
Shareholders' equity:
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	20,556,198	20,557,913
Deferred compensation trust, shares	152,964	158,894
Treasury stock at cost, shares	15,542,337	14,894,357