Note 12 - Subsequent Events (Details Textual) $ in Millions	1 Months Ended
Apr. 30, 2018 USD ($)
Astute Medical, Inc. [Member] \| Subsequent Event [Member]
Cost-method Investments, Realized Gain (Loss), Total	$ 22.5

This item represents the gain (loss) realized during the period from the sale of investments accounted for under the cost method of accounting and any losses recognized thereon for impairments of other than a temporary nature.

No definition available.

Name:	us-gaap_CostMethodInvestmentsRealizedGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration