CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 2	$ 0
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	150,000,000us-gaap_CommonStockSharesAuthorized	150,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued (in shares)	55,457,001us-gaap_CommonStockSharesIssued	54,474,594us-gaap_CommonStockSharesIssued
Common stock, shares outstanding (in shares)	54,264,483us-gaap_CommonStockSharesOutstanding	53,281,996us-gaap_CommonStockSharesOutstanding

For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.

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Face amount or stated value per share of common stock.

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