Derivative Instruments And Hedging Activities (Narrative) (Details) In Millions, unless otherwise specified	1 Months Ended
	Feb. 28, 2013 Oil And Natural Gas Commodity Contracts [Member] USD ($)	Feb. 28, 2013 Interest Rate Swaps [Member] USD ($)	Sep. 30, 2013 Interest Rate Swaps [Member] USD ($)	Feb. 28, 2013 Grand Canyon I I I [Member] USD ($)	Feb. 28, 2013 Grand Canyon I I I [Member] NOK	Feb. 28, 2013 Grand Canyon I I [Member] USD ($)	Feb. 28, 2013 Grand Canyon I I [Member] NOK	Jan. 31, 2013 Grand Canyon [Member] USD ($)	Jan. 31, 2013 Grand Canyon [Member] NOK
Derivative [Line Items]
Derivative Cash Settlement	$ 22.5	$ 0.6
Notional Amount of Derivative			$ 148.1	$ 98.8	595.0	$ 100.4	594.7	$ 104.6	591.3