Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
CURRENT ASSETS:
Allowance for doubtful accounts	$ 2,199	$ 3,202
Accumulated depreciation and amortization of property	$ 179,713	$ 166,912
SHAREHOLDERS' EQUITY:
Common shares, par value	$ 0.001	$ 0.001
Common shares, shares authorized	1,000,000,000	1,000,000,000
Common shares, shares outstanding	116,100,000	117,800,000