Note 2 - Acquisitions (Details Textual) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
	Apr. 22, 2022 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Business Combination, Bargain Purchase, Gain Recognized, Amount			$ 1,300	$ (0)	$ (0)
Warrants Issued to Acquire Swire Pacific Offshore Holdings Ltd. [Member]
Class of Warrant or Right, Issued During Period, Exercise Price (in dollars per share) | $ / shares	$ 0.001		$ 0.001
Swire Pacific Offshore Holdings Ltd. [Member]
Number of Vessels, Offshore Support	50		50
Payments to Acquire Businesses, Gross	$ 42,000
Payments to Acquire Businesses, Preclosing Working Capital Adjustments	19,600
Proceeds From Previous Acquisition, Post-closing Working Capital Refund	8,800	$ 8,800
Business Combination, Consideration Transferred, Total	215,500
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual			$ 149,700
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual			14,800
Proceeds From Previous Acquisition, Post-closing Working Capital Refund, in Excess of Original Estimate		$ 8,000
Business Combination, Acquisition Related Costs			18,800
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total	$ 171,007		$ 171,000
Property, Plant and Equipment, Original Lie of Asset (Year)			20 years
Goodwill, Ending Balance			$ 0
Business Acquisition, Pro Forma Revenue			714,783	578,506
Business Acquisition, Pro Forma Net Income (Loss)			$ (22,899)	(143,509)
Swire Pacific Offshore Holdings Ltd. [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)			1 year
Swire Pacific Offshore Holdings Ltd. [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)			16 years
Swire Pacific Offshore Holdings Ltd. [Member] | Warrants Issued to Acquire Swire Pacific Offshore Holdings Ltd. [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in shares) | shares	8,100,000		8,100,000
Sonatide [Member]
Payments to Acquire Businesses, Gross			$ 11,200
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual			$ 2,300	$ 800
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage			49.00%
Equity Method Investment, Ownership Percentage by Other Owners			51.00%
Business Acquisition, Percentage of Voting Interests Acquired			51.00%
Business Combination, Bargain Purchase, Gain Recognized, Amount			$ 1,300
Business Acquisition, Pro Forma Revenue			375,400
Business Acquisition, Pro Forma Net Income (Loss)			129,900
Sonatide [Member] | Interest Income and Other, Net [Member]
Business Combination, Bargain Purchase, Gain Recognized, Amount			$ 1,300