Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts receivable, allowance for doubtful accounts	$ 7,119	$ 8,695
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized	2,000,000us-gaap_PreferredStockSharesAuthorized	2,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	640,000,000us-gaap_CommonStockSharesAuthorized	640,000,000us-gaap_CommonStockSharesAuthorized
Common stock, issued	191,655,690us-gaap_CommonStockSharesIssued	202,553,220us-gaap_CommonStockSharesIssued
Common stock, outstanding	191,655,690us-gaap_CommonStockSharesOutstanding	202,553,220us-gaap_CommonStockSharesOutstanding

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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