CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Accounts receivable, allowance for doubtful accounts	$ 7,892	$ 7,954
Property, plant and equipment, accumulated depreciation, depletion and amortization	$ 6,861,494	$ 6,040,996
Cumulative Preferred Stock, par	$ 100	$ 100
Cumulative Preferred Stock, authorized	400,000	400,000
Cumulative Preferred Stock, issued	0	0
Common Stock, par	$ 1.00	$ 1.00
Common Stock, authorized shares	450,000,000	450,000,000
Common Stock, issued shares	193,909,200	193,293,526