Note 5. Line of Credit (Details Textual) - USD ($)	Mar. 31, 2018	Feb. 04, 2016	Jun. 23, 2015	Feb. 05, 2015	Jun. 30, 2008	Mar. 29, 2006
Credit Line, 2006 [Member] | Silicon Valley Bank [Member]
Line of Credit Facility, Maximum Borrowing Capacity						$ 1,000,000
Credit Line, 2008 [Member] | Silicon Valley Bank [Member]
Line of Credit Facility, Maximum Borrowing Capacity					$ 2,500,000
Line of Credit [Member] | Silicon Valley Bank [Member]
Line of Credit Facility, Maximum Borrowing Capacity			$ 625,000
Line of Credit Facility, Maximum Borrowing Capacity	$ 2,200,000	$ 2,200,000		$ 2,200,000