CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Allowances on accounts receivable, current	$ 5,426	$ 5,447
Accumulated depreciation on property and equipment	569,821	555,030
Accumulated amortization on other intangible assets	$ 202,780	$ 198,082
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	221,384,192	220,917,050
Common stock, shares outstanding	209,440,854	209,270,586
Treasury stock, common shares	11,943,338	11,646,464
Exchangeable Shares [Member]
Exchangeable Shares, par value
Common stock, shares issued	3,500,000	3,909,110
Common stock, shares outstanding	3,500,000	3,909,110
Series F Preferred Stock [Member]
Preferred stock, par value	$ 0.00001	$ 0.00001
Preferred stock, shares authorized	1	1
Preferred stock, shares issued	1	1
Preferred stock, shares outstanding	1	1