Note 7 - Contract Assets and Liabilities - Component of Contract Asset and Liability Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Costs in excess of billings and estimated earnings	$ 61,815	$ 39,300	$ 39,623
Contract retention	142,231	125,639	120,316
Total contract assets	204,046	164,939	159,939
Billings in excess of costs and estimated earnings, net of retention	166,091	143,623	168,383
Provisions for losses	29,176	27,698	21,047
Total contract liabilities	$ 195,267	$ 171,321	$ 189,430