Summary Of Significant Accounting Policies (Property, Plant And Equipment) (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010	Mar. 30, 2012 item
Summary Of Significant Accounting Policies [Abstract]
Capitalized interest on the cost of major capital projects	$ 12.4	$ 7.1	$ 2.7
Amount of liftboat components wrote off			32.0
Reduction in the value of property, plant and equipment		$ 35.8
Number of liftboats sold				18
Number of components partially completed	2