Note 9 - Construction Joint Ventures (Details Textual) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Contract Value of Active Construction Joint Venture Projects	$ 3,000,000								$ 3,000,000
Contract with Customer, Liability, Total	200,041				$ 162,925				200,041	$ 162,925	$ 85,293
Revenue from Contract with Customer, Including Assessed Tax	683,196	$ 925,854	$ 834,671	$ 566,332	830,390	$ 955,761	$ 811,866	$ 530,862	3,010,053	3,128,879	2,914,877
Retained Earnings (Accumulated Deficit), Ending Balance	$ 410,831				424,835				410,831	424,835
Unconsolidated Construction Joint Venture Net Income (Loss)									$ (765)	(51,486)	(120,632)
Unconsolidated Construction Corporate Joint Venture [Member]
Number of Active Joint Venture Projects	9								9
Contract Value of Active Construction Joint Venture Projects	$ 10,700,000								$ 10,700,000
Contract with Customer, Liability, Total	180,200								180,200
Affirmative Claim Recovery Estimate	103,800				88,700				103,800	88,700
Back Charge Claims	10,700				13,100				10,700	13,100
Retained Earnings (Accumulated Deficit), Ending Balance	28,600				82,500				28,600	82,500
Unconsolidated Construction Corporate Joint Venture [Member] | Minimum [Member]
Contract Value of Active Construction Joint Venture Projects	13,700								13,700
Contract with Customer, Liability, Total	$ 1,200								$ 1,200
Equity Method Investment, Ownership Percentage	20.00%								20.00%
Unconsolidated Construction Corporate Joint Venture [Member] | Maximum [Member]
Contract Value of Active Construction Joint Venture Projects	$ 3,800,000								$ 3,800,000
Contract with Customer, Liability, Total	$ 43,200								$ 43,200
Equity Method Investment, Ownership Percentage	50.00%								50.00%
Unconsolidated Construction Corporate Joint Venture [Member] | Performance Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 300,000								$ 300,000
Guarantor Obligations, Current Carrying Value	82,100				$ 82,300				82,100	82,300
Co-venturer [Member] | Performance Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	400,000								400,000
Consolidated Construction Corporate Joint Venture [Member]
Contract Value of Active Construction Joint Venture Projects	$ 939,800								$ 939,800
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Number of Active Joint Venture Projects	8								8
Contract Value of Active Construction Joint Venture Projects		$ 1,600,000
Contract with Customer, Liability, Total	$ 267,000								$ 267,000
Revenue from Contract with Customer, Including Assessed Tax									405,100	312,500	261,200
Net Cash Provided by (Used in) Continuing Operations, Total									(4,100)	(3,000)	(13,100)
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Minimum [Member]
Contract Value of Active Construction Joint Venture Projects	2,300								2,300
Contract with Customer, Liability, Total	600								$ 600
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage									50.00%
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Contract Value of Active Construction Joint Venture Projects	436,300								$ 436,300
Contract with Customer, Liability, Total	83,300								$ 83,300
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage									70.00%
Line Item Joint Venture [Member]
Contract Value of Active Construction Joint Venture Projects	221,000								$ 221,000
Contract with Customer, Liability, Total	$ 70,900								70,900
Revenue from Contract with Customer, Including Assessed Tax									67,800	80,800	18,700
Unconsolidated Construction Joint Venture Net Income (Loss)									337,100
Construction [Member]
Revenue from Contract with Customer, Including Assessed Tax									2,602,306	$ 2,764,094	$ 2,575,791
Construction [Member] | Unconsolidated Construction Corporate Joint Venture [Member]
Contract with Customer, Liability, Revenue Recognized									$ 700,000