Note 12 - Correction of Prior Period Immaterial Error (Details Textual) - USD ($)	Jan. 01, 2018	Jun. 30, 2018	Dec. 31, 2017
Retained Earnings (Accumulated Deficit), Ending Balance		$ 3,156,000	$ 2,947,000
Accounting Standards Update 2014-09 [Member]
Cumulative Effect on Retained Earnings, before Tax	$ 5,000,000
Cumulative Effect on Retained Earnings, Tax	1,200,000
Deferred Tax Liabilities, Net, Noncurrent	$ 1,200,000
Accounting Standards Update 2014-09 [Member] | Errors Related to Not Recording Tax Effect of ASC 606 [Member]
Deferred Tax Liabilities, Net, Noncurrent		1,200,000
Retained Earnings (Accumulated Deficit), Ending Balance		$ (1,200,000)