Commitments and Contingencies (Details Textuals) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2011	Dec. 31, 2010	Jun. 30, 2011	Dec. 31, 2009	Sep. 14, 2006
Commitments and Contingencies (Textuals) [Abstract]
Assessed income tax amount of NDIL's Mexico branch					$ 19,800,000
Potential tax assessments range			$6 million to $26 million per year for the period from 2005 to 2009
Unrecognized tax benefits reductions resulting from lapse of applicable statute of limitations		7,400,000
Alleged customs infractions amount				19,700,000
Amount of loss range, minimum				140,000
Payment of attorney's fees in full settlement			475,000
Possible Loss Relating to Foreign Currency Exchange Control	39,100,000
Payment of Contract Amount in Foreign Currency	7,500,000
Payment of Contract Amount in Domestic Currency	3,200,000
Potential judgement in excess of accrual	31,100,000
Period within which payment received			30 days
Minimum Range [Member]
Income Tax Examination [Line Items]
Aggregate potential tax assessments range			90,000,000
Maximum Range [Member]
Income Tax Examination [Line Items]
Aggregate potential tax assessments range			95,000,000
Messrs.Isenberg [Member]
Commitments and Contingencies (Textuals) [Abstract]
Amount of payment due to death, disability or termination			100,000,000
Petrello [Member]
Commitments and Contingencies (Textuals) [Abstract]
Amount of payment due to death, disability or termination			50,000,000
Approximate amount of payment due to death, disability or termination			$ 34,000,000