Commitments and Contingencies - Additional Information - Randgrid (Detail)	Jun. 30, 2016
Randgrid shuttle tanker [Member]
Loss Contingencies [Line Items]
Percentage of ownership by non-controlling owners	33.00%

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.

No definition available.

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration