Note 11 - Construction Joint Ventures (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Contract Value of Active Construction Joint Venture Projects	$ 2,500,000		$ 2,500,000
Contract with Customer, Liability, Total	191,037	$ 195,267	191,037	$ 195,267	$ 200,041	[1]
Revenue from Contract with Customer, Including Assessed Tax	1,009,806	1,062,129	2,514,194	2,696,214
Retained Earnings (Accumulated Deficit), Total	481,489	430,074	481,489	430,074	410,831
Unconsolidated Construction Corporate Joint Venture [Member]
Contract with Customer, Liability, Total	86,100		86,100
Minimum [Member] | Unconsolidated Construction Corporate Joint Venture [Member]
Contract with Customer, Liability, Total	$ 700		$ 700
Equity Method Investment, Ownership Percentage	23.00%		23.00%
Maximum [Member] | Unconsolidated Construction Corporate Joint Venture [Member]
Contract with Customer, Liability, Total	$ 34,600		$ 34,600
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Unconsolidated Construction Corporate Joint Venture [Member]
Number of Active Joint Venture Projects	7		7
Contract Value of Active Construction Joint Venture Projects	$ 8,900,000		$ 8,900,000
Affirmative Claim Recovery Estimate	95,800	101,900	95,800	101,900	103,800
Back Charge Claims	2,700	14,100	2,700	14,100	10,700
Retained Earnings (Accumulated Deficit), Total	7,900	19,900	7,900	19,900	28,600
Unconsolidated Construction Corporate Joint Venture [Member] | Minimum [Member]
Contract Value of Active Construction Joint Venture Projects	12,300		12,300
Unconsolidated Construction Corporate Joint Venture [Member] | Maximum [Member]
Contract Value of Active Construction Joint Venture Projects	3,800,000		3,800,000
Unconsolidated Construction Corporate Joint Venture [Member] | Performance Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	86,100		86,100
Guarantor Obligations, Current Carrying Value	77,400	82,300	77,400	82,300	$ 82,100
Co-venturer [Member] | Performance Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	156,100		156,100
Consolidated Construction Corporate Joint Venture [Member]
Contract Value of Active Construction Joint Venture Projects	$ 1,000,000		$ 1,000,000
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Number of Active Joint Venture Projects	9		9
Contract Value of Active Construction Joint Venture Projects	$ 1,800,000		$ 1,800,000
Contract with Customer, Liability, Total	166,800		166,800
Revenue from Contract with Customer, Including Assessed Tax	117,500	117,400	344,500	314,900
Net Cash Provided by (Used in) Continuing Operations, Total			4,700	17,500
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Minimum [Member]
Contract Value of Active Construction Joint Venture Projects	12,000		12,000
Contract with Customer, Liability, Total	3,000		$ 3,000
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	436,200		$ 436,200
Contract with Customer, Liability, Total	38,100		$ 38,100
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage			70.00%
Construction [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 848,267	$ 924,454	$ 2,141,009	$ 2,369,848
Construction [Member] | Unconsolidated Construction Corporate Joint Venture [Member]
Contract with Customer, Liability, Revenue Recognized			$ 242,200

[1] These balances do not include amounts held for sale (see Note 3).