Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Statement of Financial Position [Abstract]
Trade receivables allowances	$ 18,908	$ 19,028	$ 6,687
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, shares outstanding	46,461,504	46,317,433	45,932,034