Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
CURRENT ASSETS
Allowance for doubtful accounts	$ 24,157	$ 15,599
Allowance for depreciation	$ 759,800	$ 729,187
EQUITY:
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	450,000,000	450,000,000
Common stock, shares issued	156,766,944	157,636,261