Note 10 - Fair Value Measurement (Details) - Financial Assets and Liabilities, Fair Value (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Assets:
Assets	$ 194,640us-gaap_AssetsFairValueDisclosure	$ 180,155us-gaap_AssetsFairValueDisclosure
Liabilities:
Contingent consideration	2,507	2,507
Total	2,507us-gaap_LiabilitiesFairValueDisclosure	2,507us-gaap_LiabilitiesFairValueDisclosure
Money Market Funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets:
Assets	46,965	60,078
Money Market Funds [Member]
Assets:
Assets	46,965	60,078
Certificates of Deposit [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets:
Assets	23,050	22,778
Certificates of Deposit [Member]
Assets:
Assets	23,050	22,778
US Government Agencies Short-term Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets:
Assets	114,741	89,674
US Government Agencies Short-term Debt Securities [Member]
Assets:
Assets	114,741	89,674
Auction Rate Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets:
Assets	5,394	5,389
Auction Rate Securities [Member]
Assets:
Assets	5,394	5,389
Equity Funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets:
Assets	4,490	2,236
Equity Funds [Member]
Assets:
Assets	4,490	2,236
Fair Value, Inputs, Level 1 [Member]
Assets:
Assets	51,455	62,314
Fair Value, Inputs, Level 2 [Member]
Assets:
Assets	137,791	112,452
Fair Value, Inputs, Level 3 [Member]
Assets:
Assets	5,394	5,389
Liabilities:
Contingent consideration	2,507	2,507
Total	$ 2,507	$ 2,507

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

+ References

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)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 35

-Paragraph 1

-Subparagraph b

-URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 25

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

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- Definition

Fair value of financial and nonfinancial obligations.

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