Summary Of Major Accounting Policies - Property, Plant and Equipment (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Interest Costs, Capitalized, Minimum Construction Period	3 months
Interest Costs, Capitalized During Period	$ 0	$ 0	$ 0.3
Asset Impairment Charges			$ 5.2
Remotely Operated Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Average	8 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Cash and Cash Equivalents, Short-term Investments, Maturity Period	3 months
Maximum [Member] | Marine Services Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Average	20 years
Maximum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Average	25 years
Minimum [Member] | Marine Services Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Average	3 years
Minimum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Average	3 years