Note 1 - Summary of Significant Accounting Policies 1 (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended									6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)		Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Jun. 30, 2022 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($)		Dec. 31, 2020 USD ($) $ / shares	Jan. 01, 2022 USD ($)	Nov. 30, 2019
Revenue, Remaining Performance Obligation, Amount	$ 2,877,478				$ 2,595,085	[1]						$ 2,877,478	$ 2,595,085	[1]
Revenue from Contract with Customer, Including Assessed Tax	789,213	$ 1,008,910	$ 849,247	$ 653,886	805,651		$ 1,062,129	$ 964,172	$ 669,913	$ 1,503,133	$ 2,512,043	3,301,256	3,501,865		$ 3,562,459
Capitalized Computer Software, Additions												11,400	12,000		7,400
Goodwill, Impairment Loss															$ 147,100
Share Price, Potential Dilutive Effect (in dollars per share) | $ / shares															$ 31.47
Deferred Tax Assets, Net of Valuation Allowance, Total	$ 86,441				$ 102,991							$ 86,441	102,991
Accounting Standards Update 2020-06 [Member]
Long-Term Debt, Gross																$ 22,000
Deferred Tax Assets, Net of Valuation Allowance, Total																5,600
Additional Paid in Capital, Total																$ (16,400)
Warrants Issued With 2.75% Convertible Notes [Member]
Share Price, Potential Dilutive Effect (in dollars per share) | $ / shares												$ 53.44
Central Group Construction [Member]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	80.00%											80.00%
Water Resources and Mineral Services [Member]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	40.00%											40.00%
Minimum [Member]
Finite-Lived Intangible Assets, Remaining Amortization Period (Year)												2 years
Construction Contracts, Warranty Provisions Period (Month)												2 months
Construction Contracts, Longer Warranty Periods (Year)												2 years
Workers' Compensation Liability	$ 500											$ 500
Maximum [Member]
Finite-Lived Intangible Assets, Remaining Amortization Period (Year)												15 years
Construction Contracts, Longer Warranty Periods (Year)												10 years
Workers' Compensation Liability	$ 1,500											$ 1,500
Construction Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)												3 years
Construction Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)												10 years
Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)												2 years
Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)												20 years
Software and Software Development Costs [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)												3 years
Software and Software Development Costs [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)												7 years
Foreign Affiliates [Member]
Equity Method Investment, Other than Temporary Impairment															$ 9,600
Caltrans [Member]
Revenue from Contract with Customer, Including Assessed Tax												$ 348,000	$ 337,100		$ 316,900
Caltrans [Member] | Product Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk, Percentage												10.50%	9.60%		8.90%
The 2.75% Convertible Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage	2.75%				2.75%							2.75%	2.75%		2.75%		2.75%
Debt Instrument, Interest Rate, Effective Percentage	6.62%											6.62%
Other Current Assets [Member]
Deposit for Legal Settlements					$ 129,000								$ 129,000
Continuing Operations [Member]
Revenue, Remaining Performance Obligation, Amount	$ 2,900,000				$ 2,600,000							$ 2,900,000	$ 2,600,000
Number of Reporting Units													5

[1] These balances do not include amounts held for sale (see Note 2).