Note 7 - Accounting for Share-based Payment Arrangement Compensation (Details Textual) - USD ($)	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Stock or Unit Option Plan Expense	$ 290,000	$ 273,000

The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Name:	us-gaap_StockOptionPlanExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration