LONG-TERM DEBT AND NOTES PAYABLE - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended		12 Months Ended				1 Months Ended		12 Months Ended	1 Months Ended			1 Months Ended											1 Months Ended
	Aug. 31, 2011	Dec. 31, 2011	Dec. 31, 2011 North Ocean Construction Financing North Ocean 102	Dec. 31, 2010 North Ocean Construction Financing North Ocean 102	Dec. 31, 2011 JRMSA	Dec. 31, 2010 JRMSA	Aug. 31, 2011 Minimum	Aug. 31, 2011 Maximum	Dec. 31, 2011 Revolving Credit Facility	Aug. 31, 2011 Revolving Credit Facility Before Amendment	Aug. 31, 2011 Revolving Credit Facility After Amendment	Aug. 31, 2011 Revolving Credit Facility After Amendment Pro Forma	Aug. 31, 2011 Base rate	Dec. 31, 2011 Financial Letter of Credit	Aug. 31, 2011 Financial Letter of Credit Minimum	Aug. 31, 2011 Financial Letter of Credit Maximum	Dec. 31, 2011 Performance Letters of Credit	Aug. 31, 2011 Performance Letters of Credit Minimum	Aug. 31, 2011 Performance Letters of Credit Maximum	Dec. 31, 2011 Unsecured Debt	Dec. 31, 2011 Eurodollar rate	Dec. 31, 2011 Base Rate Loans	Dec. 31, 2011 Commitments	Sep. 30, 2010 Secured Debt North Ocean Construction Financing North Ocean 105 Installment	Dec. 31, 2011 Secured Debt North Ocean Construction Financing North Ocean 105	Dec. 31, 2010 Secured Debt North Ocean Construction Financing North Ocean 105	Sep. 30, 2010 Secured Debt Maximum North Ocean Construction Financing North Ocean 105
Debt Instrument [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										400.0	600.0
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		0.34								2.5	3	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 outstanding, margin over Federal Fund rate													0.50%
Interest on loan outstanding, margin over Eurodollar rate							1.50%	2.50%					1.00%
Interest on loan outstanding, margin over base rate							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%				0.30%
Revolving credit, borrowings outstanding									0
Letters of credit outstanding amount									306.1											219.0
Credit facility, current borrowing capacity									643.9
Credit facility, applicable interest rate									4.25%
Applicable margin																					2.00%	1.00%
Business acquisition percentage, interests acquired																								75.00%
Notes payable			43.3	51.9
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.
Number of consecutive semi-annual installments																								17
Borrowing outstanding																									50.4	3.4
Notes payable, current			6.0	8.5																					2.9
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
Bonds issued					$ 19.5	$ 5.1