|
Business Operations - Revenues and Percentage of Consolidated Revenue (Detail) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2013
|
Dec. 31, 2012
|
Dec. 31, 2011
|
|
| Revenue, Major Customer [Line Items] | |||
| Revenue of significant customer | $ 170,087 | $ 197,429 | $ 215,072 |
|
Hyundai Merchant Marine Co. Ltd. [Member] | Customer Concentration Risk [Member]
|
|||
| Revenue, Major Customer [Line Items] | |||
| Revenue of significant customer | 22,500 | ||
|
Statoil ASA [Member] | Customer Concentration Risk [Member]
|
|||
| Revenue, Major Customer [Line Items] | |||
| Revenue of significant customer | 33,700 | 27,300 | 23,700 |
|
ConocoPhillips [Member] | Customer Concentration Risk [Member]
|
|||
| Revenue, Major Customer [Line Items] | |||
| Revenue of significant customer | $ 18,100 | $ 31,800 | $ 33,100 |