Cash, Cash Equivalents and Investments, Fair Value Measurements, Recurring and Nonrecurring (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets [Abstract]
Cash and cash equivalents, fair value disclosure	$ 28,814	$ 24,961
Available-for-sale Securities, Fair Value Disclosure	48,937us-gaap_AvailableForSaleSecurities	47,605us-gaap_AvailableForSaleSecurities
Recurring [Member]
Assets [Abstract]
Assets, fair value	20,146	22,753
Liabilities [Abstract]
Liabilities, fair value	0	0
Recurring [Member] \| Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Assets, fair value	777	2,157
Liabilities [Abstract]
Liabilities, fair value	0	0
Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Assets, fair value	19,369	20,596
Liabilities [Abstract]
Liabilities, fair value	0	0
Recurring [Member] \| Money market fund - cash [Member]
Assets [Abstract]
Cash and cash equivalents, fair value disclosure	23	109
Recurring [Member] \| Money market fund - cash [Member] \| Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Cash and cash equivalents, fair value disclosure	23	109
Recurring [Member] \| Money market fund - cash [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Cash and cash equivalents, fair value disclosure	0	0
Recurring [Member] \| Certificates of deposit [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	10,183	6,318
Recurring [Member] \| Certificates of deposit [Member] \| Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0	0
Recurring [Member] \| Certificates of deposit [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	10,183	6,318
Recurring [Member] \| Corporate bonds [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	9,186	14,278
Recurring [Member] \| Corporate bonds [Member] \| Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	0	0
Recurring [Member] \| Corporate bonds [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	9,186	14,278
Recurring [Member] \| Corporate equity security [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	754	2,048
Recurring [Member] \| Corporate equity security [Member] \| Quoted Prices in Active Markets of Identical Assets (Level 1) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	754	2,048
Recurring [Member] \| Corporate equity security [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Available-for-sale Securities, Fair Value Disclosure	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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Fair value of financial and nonfinancial obligations.

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