Note 1 - Basis of Presentation (Details Textual) - Accounting Standards Update 2016-09 [Member] - USD ($) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2017	Jan. 01, 2017
Weighted Average Number Diluted Shares Outstanding Increase	0.5
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 5.1

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

No definition available.

Name:	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant