Note 3 - Fair value Measurement - Assets Measured on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Assets, Fair Value	$ 176,475	$ 184,969
Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value	176,475	184,969
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value
Money Market Funds [Member]
Assets, Fair Value	10,833	19,812
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value	10,833	19,812
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value
Tri-party Repurchase Agreements [Member]
Assets, Fair Value	165,642	165,157
Tri-party Repurchase Agreements [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value	165,642	165,157
Tri-party Repurchase Agreements [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value
Tri-party Repurchase Agreements [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value