Note 6 - Contract Assets and Liabilities - Component of Contract Asset and Liability Balances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Costs in excess of billings and estimated earnings	$ 14,158	$ 26,199
Contract retention	131,279	105,898
Total contract assets	145,437	132,097	$ 163,578
Balance at December 31, 2020	132,097	163,578
Change in the measure of progress on projects, net	547,450	656,460
Revisions in estimates, net	(36,899)	(41,136)
Billings	(461,294)	(606,982)
Receipts related to contract retention	(35,917)	(39,823)
Balance at December 31, 2021	145,437	132,097	163,578
Billings in excess of costs and estimated earnings, net of retention	169,542	135,788
Provisions for losses	30,499	27,137
Total contract liabilities	200,041	162,925	85,293
Balance at December 31, 2020	162,925	85,293
Change in the measure of progress on projects, net	(1,770,667)	(1,748,830)
Contract with Customer, Liability, Cumulative Catch-up Adjustment to Revenue, Change in Estimate of Transaction Price	13,975	(3,856)	152,100
Billings	1,790,446	1,807,911
Change in provision for loss, net	3,362	22,407
Balance at December 31, 2021	$ 200,041	$ 162,925	$ 85,293