Note 4 - Contracts in Progress - Costs, Estimated Earnings, and Billings on Uncompleted Contracts (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Costs incurred on contracts in progress	$ 7,417,135	$ 4,678,192
Estimated earnings	16,467,264	10,733,826
Total	23,884,399	15,412,018
Billings to date	(23,841,934)	(18,077,839)
Cost in excess of billing, net	42,465	(2,665,821)
Included in accompanying balance sheets under the following captions:
Costs and estimated earnings in excess of billings on contracts in progress	3,027,086	2,596,518
Billings in excess of costs and estimated earnings on contracts in progress	(2,984,621)	(5,262,339)
Cost in excess of billing, net	$ 42,465	$ (2,665,821)