Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Statement of Financial Position [Abstract]
Trade receivables, allowances	$ 6,687	$ 6,405	$ 9,592
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, shares outstanding	45,932,034	45,777,760	45,414,157