Commitments and Contingencies - Additional Information - Navion Hispania (Detail)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2014 Navion Offshore Loading [Member] USD ($)	Dec. 31, 2013 Navion Offshore Loading [Member] USD ($)	Dec. 31, 2013 Navion Offshore Loading [Member] NOK	Dec. 31, 2014 Navion Offshore Loading [Member] Loss from Catastrophes [Member] USD ($)	Dec. 31, 2014 Navion Offshore Loading [Member] Loss from Catastrophes [Member] NOK
Long-term Purchase Commitment [Line Items]
Loss contingency, liability accrual			$ 0	$ 29,000,000	216,400,000	$ 15,800,000	117,500,000
Accounts receivable	378,193,000us-gaap_AccountsReceivableNetCurrent	528,594,000us-gaap_AccountsReceivableNetCurrent		29,000,000	216,400,000	15,800,000	117,500,000
Accounts receivable			$ 0

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3-4)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Subparagraph a(1)

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 4

-Article 5

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Period Type:	duration

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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- Definition

Amount of receivable related to a loss contingency accrual that is expected to be collected within one year or the normal operating cycle, if longer. For example, an insurance recovery receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12053-110248

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