Note 3 - Selected Balance Sheet Data (Details Textual) $ in Millions	Jun. 30, 2018 USD ($)
ChemoCentryx, Inc (CCXI) [Member]
Available-for-sale Equity Securities, Amortized Cost Basis, Total	$ 18.8

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

No definition available.

Name:	us-gaap_AvailableForSaleEquitySecuritiesAmortizedCostBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant