Note 16 - Benefit Plans - Reconciliation of Level 3 Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Balance at beginning of period	$ 58,014
Balance at end of period	61,870
Fair Value, Inputs, Level 3 [Member]
Balance at end of period	10,134
Other Investment [Member]
Balance at end of period	10,134
Other Investment [Member] | Fair Value, Inputs, Level 3 [Member]
Balance at beginning of period	9,700
Purchases	3,805
Redemptions	(3,795)
Realized gains	424
Balance at end of period	$ 10,134