Investments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investments
Amortized Cost	$ 39,461	$ 76,019
Gross Unrealized Gains	1	3
Gross Unrealized Losses	(9)
Fair Value	39,453	76,022
Cash and Cash Equivalent [Member]
Investments
Fair Value	9,470	53,306
Marketable Securities [Member]
Investments
Fair Value	29,790	22,511
Restricted Cash [Member]
Investments
Fair Value	193	205
Money Market Funds [Member]
Investments
Amortized Cost	9,663	53,511
Fair Value	9,663	53,511
US Government Corporations and Agencies Securities [Member]
Investments
Amortized Cost	13,774	12,301
Gross Unrealized Losses	(4)
Fair Value	13,770	12,301
Commercial Paper [Member]
Investments
Amortized Cost	1,499	8,246
Gross Unrealized Gains	1	3
Fair Value	1,500	8,249
Corporate Debt Securities [Member]
Investments
Amortized Cost	14,525	1,961
Gross Unrealized Losses	(5)
Fair Value	$ 14,520	$ 1,961

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

No definition available.

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- Definition

Represents the fair value of investment in debt and equity securities.

+ References

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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