Long-Term Debt and Notes Payable (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended		12 Months Ended				12 Months Ended		12 Months Ended		12 Months Ended												1 Months Ended
	Dec. 31, 2012	Apr. 20, 2012 Reimbursement Agreement	Dec. 31, 2012 Minimum	Dec. 31, 2012 Maximum	Dec. 31, 2012 Mexico	Dec. 31, 2011 Mexico	Dec. 31, 2012 North Ocean Construction Financing North Ocean 102	Dec. 31, 2011 North Ocean Construction Financing North Ocean 102	Dec. 31, 2012 Revolving Credit Facility	Dec. 31, 2011 Revolving Credit Facility	Dec. 31, 2012 Base rate	Dec. 31, 2012 Financial Letter of Credit	Dec. 31, 2012 Financial Letter of Credit Minimum	Dec. 31, 2012 Financial Letter of Credit Maximum	Dec. 31, 2012 Performance Letters of Credit	Dec. 31, 2012 Performance Letters of Credit Minimum	Dec. 31, 2012 Performance Letters of Credit Maximum	Dec. 31, 2012 Eurodollar rate	Dec. 31, 2012 Base Rate Loans	Dec. 31, 2012 Commitments	Dec. 31, 2012 Unsecured Debt	Dec. 31, 2011 Unsecured Debt	Sep. 30, 2010 Secured Debt North Ocean Construction Financing North Ocean 105 Installment	Dec. 31, 2012 Secured Debt North Ocean Construction Financing North Ocean 105	Dec. 31, 2011 Secured Debt North Ocean Construction Financing North Ocean 105	Sep. 30, 2010 Secured Debt North Ocean Construction Financing North Ocean 105 Maximum
Debt Instrument [Line Items]
Letters of credit aggregate borrowing capacity				$ 950.0
Credit facility, maturity date	Aug. 19, 2016
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 Eurodollar rate			1.50%	2.50%							1.00%
Interest on loan outstanding, margin over Federal Fund rate											0.50%
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												1.75%	1.50%	2.50%	0.875%	0.75%	1.25%			0.25%
Revolving credit, borrowings outstanding									0
Letters of credit outstanding amount		109.0							267.3	306.1											117.6	219.0
Credit facility, current borrowing capacity									682.7
Credit facility, applicable interest rate									4.00%
Applicable margin																		1.75%	0.75%
Notes payable							37.3	43.3
Notes payable, current							6.0	6.0																8.2	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
Business acquisition percentage, interests acquired																							75.00%
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, which commenced on October 1, 2012.
Number of consecutive semi-annual installments																							17
Borrowing outstanding																								65.4	50.4
Bonds issued related to JRMSA general agreement of indemnity					$ 50.1	$ 19.5