Income Tax Expenses - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Interest and penalties on freight tax expenses (recoveries)	$ 8.4	$ 5.4
Foreign exchange gains on freight tax expenses	$ 0.6	$ 3.3

Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

Name:	us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration