Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Allowances on accounts receivable, current	$ 6,174	$ 5,215
Accumulated depreciation on property and equipment	739,545	631,939
Accumulated amortization on other intangible assets	$ 255,858	$ 223,355
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	226,194,656us-gaap_CommonStockSharesIssued	224,968,797us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	210,819,790us-gaap_CommonStockSharesOutstanding	212,942,767us-gaap_CommonStockSharesOutstanding
Treasury stock, common shares	15,374,866us-gaap_TreasuryStockShares	12,026,030us-gaap_TreasuryStockShares
Exchangeable Shares [Member]
Exchangeable Shares, par value	$ 0	$ 0
Common stock, shares issued	7,325,971	3,500,000
Common stock, shares outstanding	7,325,971	3,500,000
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	0
Preferred stock, shares issued	1	0
Preferred stock, shares outstanding	1	0

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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