Note 2 - Adoption of New Accounting Standard (Details Textual)	3 Months Ended
	Mar. 31, 2018	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Cumulative Effect of New Accounting Principle in Period of Adoption			$ 485,000
Number of Reportable Segments	4
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption			$ 485,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 485,000