Note 4 - Fair Value: Fair Value Measurements, by Fair Value hierarchy (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Corporate Debt Securities
Investments, Fair Value Disclosure	$ 371,140	$ 311,442
US States and Political Subdivisions Debt Securities
Investments, Fair Value Disclosure	217,735,663	211,888,274
Investments, Fair Value Disclosure	218,106,803	212,199,716
Fair Value, Inputs, Level 1 | Corporate Debt Securities
Investments, Fair Value Disclosure	371,140	311,442
Fair Value, Inputs, Level 1 | US States and Political Subdivisions Debt Securities
Investments, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1
Investments, Fair Value Disclosure	371,140	311,442
Fair Value, Inputs, Level 2 | Corporate Debt Securities
Investments, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 | US States and Political Subdivisions Debt Securities
Investments, Fair Value Disclosure	217,735,663	211,888,274
Fair Value, Inputs, Level 2
Investments, Fair Value Disclosure	217,735,663	211,888,274
Fair Value, Inputs, Level 3 | Corporate Debt Securities
Investments, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 | US States and Political Subdivisions Debt Securities
Investments, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3
Investments, Fair Value Disclosure	$ 0	$ 0