Schedule of Amounts Due from Affiliate (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Schedule Of Equity Method Investments [Line Items]
Begining balance	$ 132,951
Ending balance	124,757
Sonatide Marine, Ltd.
Schedule Of Equity Method Investments [Line Items]
Begining balance	109,176
Revenue earned by the company through Sonatide	41,184
Less amounts received from Sonatide	(45,393)
Less amounts used to offset Due to Sonatide obligations	(10,551)	[1]
Other	(2,615)
Ending balance	$ 91,801

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