Segment Reporting - Schedule of Company's Revenue and Income From Operations by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 550,543	$ 534,681	$ 276,193
Voyage expenses	(53,604)	(18,727)	(9,968)
Vessel operating expenses	(182,598)	(137,164)	(98,403)
Time-charter hire expense	(59,647)	(74,898)	(32,706)
Depreciation and amortization	(104,149)	(73,760)	(53,292)
General and administrative expenses	(33,199)	(30,403)	(25,130)
(Loss) gain on sale of vessels	(20,594)	771	9,955
Restructuring charge	0	(6,795)	(812)
Income (loss) from operations	96,752	193,705	65,837
Equity income	7,680	11,528	$ 4,951
Ship-to-Ship Transfer [Member]
Segment Reporting Information [Line Items]
Revenues	37,900	17,700
Operating Segments [Member] \| Conventional Tanker [Member]
Segment Reporting Information [Line Items]
Revenues	512,608	516,943
Voyage expenses	(56,805)	(18,379)
Vessel operating expenses	(150,100)	(123,572)
Time-charter hire expense	(57,368)	(74,860)
Depreciation and amortization	(99,024)	(72,118)
General and administrative expenses	(29,432)	(28,418)
(Loss) gain on sale of vessels	(20,926)	771
Restructuring charge		(6,468)
Income (loss) from operations	98,953	193,899
Equity income	7,680	11,528
Operating Segments [Member] \| Ship-to-Ship Transfer [Member]
Segment Reporting Information [Line Items]
Revenues	41,136	18,587
Voyage expenses	0	(348)
Vessel operating expenses	(32,498)	(14,441)
Time-charter hire expense	(2,279)	(38)
Depreciation and amortization	(5,125)	(1,642)
General and administrative expenses	(3,767)	(1,985)
(Loss) gain on sale of vessels	332	0
Restructuring charge		(327)
Income (loss) from operations	(2,201)	(194)
Equity income	0	0
Inter-segment Adjustment [Member]
Segment Reporting Information [Line Items]
Revenues	(3,201)	(849)
Voyage expenses	3,201	0
Vessel operating expenses	0	849
Time-charter hire expense	0	0
Depreciation and amortization	0	0
General and administrative expenses	0	0
(Loss) gain on sale of vessels	0	0
Restructuring charge		0
Income (loss) from operations	0	0
Equity income	$ 0	0
Estimated costs incurred		$ 25

Lightering Support Services, Cost per Voyage

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Total costs related to services rendered by an entity during the reporting period.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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