Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Allowances on accounts receivable, current	$ 2,719	$ 5,226
Accumulated depreciation on property and equipment	824,108	755,272
Accumulated amortization on other intangible assets	$ 283,889	$ 264,674
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	228,951,159	227,898,509
Common stock, shares outstanding	144,194,115	152,907,166
Treasury stock, common shares	84,757,044	74,991,343
Exchangeable Shares [Member]
Exchangeable Shares, par value
Common stock, shares issued	6,876,042	6,876,042
Common stock, shares outstanding	6,876,042	6,876,042
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
Series G 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