Note 11 - Related Party Transactions (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Ameritas Life Insurance Corp [Member]
Related Party Transaction, Amounts of Transaction	$ 232,000	$ 227,000	$ 207,000
Nebraska Global Investment Company LLC [Member]
Related Party Transaction, Amounts of Transaction	$ 488,000	$ 440,000	$ 0
Nebraska Global Investment Company LLC [Member] | Chief Executive Officer [Member]
Officer Ownership Percentage in Vendor	14.00%