CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED BALANCE SHEETS
Trade accounts receivable, allowance for doubtful accounts (in dollars)	$ 4,514	$ 3,778
Other intangibles, accumulated amortization (in dollars)	$ 63,511	$ 58,339
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	39,493,852	39,063,327
Common stock, shares outstanding	35,754,074	36,237,562
Treasury stock, shares	3,739,778	3,295,492