Equipment Acquisitions and Dispositions - Additional Information (Details) $ in Thousands		3 Months Ended
	Jan. 12, 2021 USD ($)	Mar. 31, 2021 USD ($) Vessel	Mar. 31, 2020 USD ($)
Property Plant And Equipment [Line Items]
Payments to acquire property, plant, and equipment, including fair value hedges		$ 2,700
Number of equipment acquired | Vessel		0
Proceeds from disposition of property and equipment		$ 3,266	$ 3,105
Deposits for future vessel sales		$ 1,700
Platform Supply Vessels
Property Plant And Equipment [Line Items]
Number of equipment sold | Vessel		1
Fast Support Vessels
Property Plant And Equipment [Line Items]
Number of equipment sold | Vessel		2
Platform Supply Vessels and Fast Support Vessels
Property Plant And Equipment [Line Items]
Proceeds from disposition of property and equipment		$ 1,600
Gain (loss) on disposition of property, plant and equipment		$ (2,400)
Anchor Handling Towing Supply
Property Plant And Equipment [Line Items]
Number of equipment sold | Vessel		2
Vessel Under Construction
Property Plant And Equipment [Line Items]
Proceeds from disposition of property and equipment		$ 2,200
Gain (loss) on disposition of property, plant and equipment		1,100
Proceeds from property, plant, and equipment, including deposits and gain on sale		3,100
Proceeds from deposits		900
Deposits for future sales		$ 2,100
Windcat Workboats
Property Plant And Equipment [Line Items]
Proceeds from disposition of property and equipment	$ 38,715
Gain (loss) on disposition of property, plant and equipment	$ 22,756