LONG-TERM DEBT AND NOTES PAYABLE - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	9 Months Ended			12 Months Ended			9 Months Ended				1 Months Ended								1 Months Ended
	Aug. 31, 2011	Sep. 30, 2011	Sep. 30, 2011 Oceanteam ASA	Sep. 30, 2010 North Ocean Construction Financing Member	Dec. 31, 2010 North Ocean Construction Financing Member Secured Debt	Sep. 30, 2011 North Ocean Construction Financing Member Secured Debt	Sep. 30, 2010 North Ocean Construction Financing Member Secured Debt	Sep. 30, 2011 Revolving Credit Facility	Sep. 30, 2011 Revolving Credit Facility Before Amendment	Sep. 30, 2011 Revolving Credit Facility After Amendment	Sep. 30, 2011 Revolving Credit Facility After Amendment Pro Forma	Aug. 31, 2011 Base rate	Sep. 30, 2011 Financial Letter of Credit	Aug. 31, 2011 Financial Letter of Credit Minimum	Aug. 31, 2011 Financial Letter of Credit Maximum	Sep. 30, 2011 Performance Letters of Credit	Aug. 31, 2011 Performance Letters of Credit Minimum	Aug. 31, 2011 Performance Letters of Credit Maximum	Sep. 30, 2011 Unsecured Debt	Aug. 31, 2011 Minimum	Aug. 31, 2011 Maximum
Debt Disclosure [Line Items]
Credit facility, maturity date									May 03, 2014	Aug. 19, 2016
Revolving loan and letter of credit commitments borrowing capacity									$ 900	$ 950
Permitted capital expenditures									400	600
Debt covenant description										Permits the incurrence of unsecured debt so long as we are in pro forma compliance with a maximum 2.751.00 leverage ratio, which replaced a pre-existing limit of $400.0 million on unsecured debt, and increased the maximum permitted leverage ratio from 2.501.00 to 3.001.00;
Permitted leverage ratio, maximum									2.50	3.00	2.75
Restricted payment, maximum									50	100
Interest on outstanding loan balance	Loans outstanding under the Credit Agreement bear interest at the borrower’s option at either the Eurodollar rate plus a margin ranging from 1.50% to 2.50% per year or the base rate (the highest of the Federal Funds rate plus 0.50%, the 30-day Eurodollar rate plus 1.0%, or the administrative agent’s prime rate) plus a margin ranging from 0.50% to 1.50% per year. The applicable margin for revolving loans varies depending on the credit ratings of the Credit Agreement.
Interest on loan outsanding, margin over Fedreal Fund rate												0.50%
Interest on loan outsanding, margin over Eurodollar rate		2.00%										1.00%								1.50%	2.50%
Interest on loan outsanding, margin over base rate		1.00%																		0.50%	1.50%
Commitment fee on the unused portion of credit agreement																				0.20%	0.45%
Letter of credit fee													2.00%	1.50%	2.50%	1.00%	0.75%	1.25%
Revolving credit, borrowings outstanding								0
Letters of credit outstanding amount								304.9											275.8
Credit facility, current borrowing capacity								645.1
Credit facility, applicable interest rate								4.25%
Commitment fee on the unused portion of credit agreement								0.30%
Notes payable			45.5
Notes payable, current			6.6
Percentage of debt guaranteed by JRMSA			50.00%
Debt description			The outstanding debt bears interest at a rate equal to the three-month LIBOR (which resets every three months) plus a margin of 2.815% and matures in January 2014.
Applicable margin for LIBOR borrowing			2.815%
Debt Maturity Date			2014-01
Secured debt							69.4
Secured debt, applicable interest rate					2.76%
Principal repayment					The agreement provides for borrowings of up to $69.4 million, bearing interest at 2.76% per year, and requires principal repayment in 17 consecutive semi-annual installments commencing on the earlier of nine months after the delivery date of the vessel and October 1, 2012.
Borrowing outstanding					$ 3.4	$ 43.6
Percentage Of Ownership Interests				75.00%