Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts receivable, trade, allowance for doubtful accounts	$ 4,276	$ 931
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	45,000,000us-gaap_PreferredStockSharesAuthorized	45,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Treasury stock, shares	1,210,271us-gaap_TreasuryStockShares	898,447us-gaap_TreasuryStockShares
Common Class A [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	360,000,000	360,000,000
Common Stock, Shares, Issued	61,762,944	61,692,561
Common Stock, Shares, Outstanding	60,552,673	60,794,114
Common Class B [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	90,000,000	90,000,000
Common Stock, Shares, Issued	11,484,408	11,484,408
Common Stock, Shares, Outstanding	11,484,408	11,484,408

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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