Note 4 - Revisions in Estimates - Summary of Impact of Revisions in Estimates to Gross Profit (Details) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2021 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares
Gross Profit, Total	$ 116,946	$ 88,343	$ 180,264	$ 112,142
Decrease to project profitability	$ (71,366)	$ 2,755	$ 16,412	$ 90,003
Diluted (in dollars per share) | $ / shares	$ 1.14	$ 0.07	$ (0.26)	$ (1.36)
Estimated Cost Recovery of Customer Affirmative Claims and Back Charges [Member]
Number of projects with downward estimate changes	0	3	2	5
Gross Profit, Total	$ 0		$ 5,000	$ 5,000
Decrease to project profitability	0	$ 30,900	11,400	69,800
Increase to net loss	$ 0	$ 22,900	$ 8,900	$ 51,800
Diluted (in dollars per share) | $ / shares	$ 0	$ 0.50	$ 0.20	$ 1.14
Estimated Cost Recovery of Customer Affirmative Claims and Back Charges [Member] | Minimum [Member]
Gross Profit, Total		$ 5,800	$ 5,300	$ 7,400
Estimated Cost Recovery of Customer Affirmative Claims and Back Charges [Member] | Maximum [Member]
Gross Profit, Total		$ 16,100	$ 6,100	$ 19,800