Summary of Long-Term Debt Obligations (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Long-term debt consists of:
Long-term borrowing	$ 94,141	$ 102,708
Less: Amounts due within one year	41,037	14,146
Total long-term debt	53,104	88,562
North Ocean Construction Financing | North Ocean 102
Long-term debt consists of:
Long-term borrowing	32,867	37,349
North Ocean Construction Financing | North Ocean 105
Long-term debt consists of:
Long-term borrowing	$ 61,274	$ 65,359