Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Accounts receivable, allowance	$ 2,847	$ 1,807
Accumulated amortization	$ 53,756	$ 44,474
Common Stock, par value
Common Stock, shares authorized	55,000,000us-gaap_CommonStockSharesAuthorized	55,000,000us-gaap_CommonStockSharesAuthorized
Common Stock, shares issued	35,696,742us-gaap_CommonStockSharesIssued	34,929,334us-gaap_CommonStockSharesIssued
Common Stock, shares outstanding	35,696,742us-gaap_CommonStockSharesOutstanding	34,929,334us-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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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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