Condensed Consolidated Statements Of Financial Position (Parenthetical) (USD $) In Thousands, except Per Share data	Sep. 30, 2011	Dec. 31, 2010
Condensed Consolidated Statements Of Financial Position
Trade accounts receivable, allowances	$ 23,795	$ 20,991
Property and equipment, accumulated depreciation	$ 429,269	$ 352,472
Preferred stock, par value	$ 0.10	$ 0.10
Preferred stock, shares authorized	15,000	15,000
Preferred stock, issued	0	0
Class A common stock, par value	$ 0.01	$ 0.01
Class A common stock, shares authorized	1,000,000	500,000
Class A common stock, shares issued	302,084	303,941
Class A common stock, shares outstanding	302,084	303,941