Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Allowances for accounts receivable	$ 6,950	$ 9,701
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares authorized	2,000	2,000
Preferred shares, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,300,000	1,300,000
Common stock, shares outstanding	561,767	615,191