Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 46,390	$ 29,309
Gross Unrealized Gains	6	1
Gross Unrealized Losses	(10)	(3)
Fair Value	46,386	29,307
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	46,390	29,309
Fair Value	46,386	29,307
Money market mutual funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,957	9,921
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	19,957	9,921
Government agency bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,515	6,817
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(6)	0
Fair Value	7,509	6,818
United States treasuries
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,035	6,089
Gross Unrealized Gains	6	0
Gross Unrealized Losses	0	0
Fair Value	8,041	6,089
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,457	4,682
Gross Unrealized Gains		0
Gross Unrealized Losses	(4)	(3)
Fair Value	8,453	4,679
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,426	1,800
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 2,426	$ 1,800

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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