Summary Of Significant Accounting Policies (Principal Service Lives) (Details)	12 Months Ended
	Dec. 31, 2011 years
Pipeline Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life, minimum	30
Principal service life, maximum	50
Offshore Drilling Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life, minimum	15
Principal service life, maximum	30
Other [Member]
Property, Plant and Equipment [Line Items]
Principal service life, minimum	3
Principal service life, maximum	40