Schedule of Amounts Due from Affiliate (Detail) - USD ($) $ in Thousands		3 Months Ended	4 Months Ended	5 Months Ended	12 Months Ended
		Dec. 31, 2018	Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Begining balance					$ 132,951
Less impairment of due from affiliate		$ (20,083)				$ (20,083)
Ending balance		132,951			125,972	132,951
Sonatide Marine, Ltd.
Schedule of Equity Method Investments [Line Items]
Begining balance			$ 262,652	$ 252,393	109,176	230,315
Revenue earned by the company through Sonatide			34,397	40,303	52,372	56,916
Less amounts received from Sonatide			(21,019)	(28,264)	(60,486)	(76,878)
Less amounts used to offset Due to Sonatide obligations	[1]		(21,453)	(33,607)	(10,551)	(78,993)
Less impairment of due from affiliate						(20,083)
Other			(2,184)	(510)	(1,265)	(2,101)
Ending balance		$ 109,176	$ 252,393	$ 230,315	$ 89,246	$ 109,176

[1]   (A) We reduced the respective due from affiliates and due to affiliates balances each period through netting transactions based on agreement with the joint venture.