Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Sep. 30, 2011	Dec. 31, 2010
Current Assets:
Allowance for Doubtful Accounts Receivable	$ 12,867	$ 29,798
Accumulated Depreciation of Property and Equipment	$ 605,997	$ 516,565
Stockholders' Equity:
Common Stock, Par Value	$ 0.01	$ 0.01
Common Stock, Shares Authorized	200,000	200,000
Common Stock, Shares Issued	139,789	116,336
Common Stock, Shares Outstanding	137,892	114,784
Treasury Stock, Shares	1,897	1,552