Business Combination - Additional Information (Detail) $ in Thousands	4 Months Ended	5 Months Ended	12 Months Ended
	Jul. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) Vessel	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Total revenues	$ 151,369	$ 178,753	$ 486,549	$ 406,520
Net loss	$ (1,646,909)	$ (38,726)	(141,219)	(171,771)
GulfMark Term Loan Facility
Business Acquisition [Line Items]
Outstanding term loan facility			$ 100,000
GulfMark
Business Acquisition [Line Items]
Business acquisition, name of acquired entity			GulfMark
Business acquisition, date of acquisition agreement			Jul. 15, 2018
Total revenues				12,700
Net loss				$ 30,600
Business combination, stock conversion ratio			1.10
Business combination, purchase consideration			$ 385,500
Number of property and equipment acquired in business combination | Vessel			65
Property and equipment acquired in business combination			$ 360,701
Estimated remaining useful lives property and equipment			1 to 18 years
Original remaining useful lives property and equipment			20 years
GulfMark | GulfMark Term Loan Facility | General and Administrative Expense
Business Acquisition [Line Items]
Business combination related costs			$ 9,000