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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

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- Definition

Amount of increase (decrease) to assets, excluding financial assets and goodwill, lacking physical substance with a finite life for purchase accounting adjustments.

+ References

No definition available.

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- Definition

Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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- Definition

Per share or per unit amount of equity securities issued.

+ References

No definition available.

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- Definition

Number of new stock issued during the period.

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Acquisition of SPT - Additional Information (Detail) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2015 USD ($) vessel $ / shares	Jul. 31, 2015 vessel $ / shares shares	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) vessel $ / shares	Aug. 31, 2015 $ / shares	Jan. 31, 2015 $ / shares	Aug. 31, 2014 $ / shares
Business Acquisition [Line Items]
Purchase price of acquisition				$ 0	$ 31,870	$ 0
Shares issued, price per share (in dollars per share) \| $ / shares	$ 6.99	$ 6.99				$ 4.80	$ 6.65	$ 4.57	$ 4.03
Ship to Ship Transfer Business [Member]
Business Acquisition [Line Items]
Purchase price of acquisition	$ 47,300
Increase of goodwill			$ 8,100
Decrease in intangible assets			$ 8,400
Ship to Ship Transfer Business [Member] \| Class B [Member]
Business Acquisition [Line Items]
Stock Issued During Period, Shares, New Issues \| shares		6,511,812
Ship to Ship Transfer Business [Member] \| Parent Company [Member] \| Class B [Member]
Business Acquisition [Line Items]
Shares issued, price per share (in dollars per share) \| $ / shares	$ 6.99	$ 6.99
Ship to Ship Transfer Business [Member] \| Working Capital [Member]
Business Acquisition [Line Items]
Purchase price of acquisition	$ 1,800
Ship-to-ship Support Vessel [Member] \| Ship to Ship Transfer Business [Member]
Business Acquisition [Line Items]
Number of vessels \| vessel	6	6
Aframax Tankers [Member]
Business Acquisition [Line Items]
Number of vessels \| vessel						1
Time-charter [Member] \| Aframax Tankers [Member] \| Ship to Ship Transfer Business [Member]
Business Acquisition [Line Items]
Number of vessels \| vessel	1	1