Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Allowances on accounts receivable, current	$ 6,611	$ 6,174
Accumulated depreciation on property and equipment	770,798	739,545
Accumulated amortization on other intangible assets	$ 261,100	$ 255,858
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	600,000,000us-gaap_CommonStockSharesAuthorized	600,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	226,885,163us-gaap_CommonStockSharesIssued	226,194,656us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	204,495,383us-gaap_CommonStockSharesOutstanding	210,819,790us-gaap_CommonStockSharesOutstanding
Treasury stock, common shares	22,389,780us-gaap_TreasuryStockShares	15,374,866us-gaap_TreasuryStockShares
Exchangeable Shares [Member]
Exchangeable Shares, par value	$ 0	$ 0
Common stock, shares issued	7,325,971	7,325,971
Common stock, shares outstanding	7,325,971	7,325,971
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

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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