Guarantees And Indemnifications (Details) (USD $) In Millions, unless otherwise specified		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 DukeSolutions [Member]	Dec. 31, 2011 Crescent [Member]	Dec. 31, 2009 Crescent [Member]	Dec. 31, 2011 Indemnification Agreement [Member] Spectra Capital [Member]	Dec. 31, 2011 Indemnification Agreement [Member] DukeSolutions [Member]	Dec. 31, 2011 Performance Guarantee [Member]	Dec. 31, 2011 Payment Guarantee [Member]
Maximum potential amount of future payments associated with guarantees					$ 206.0	$ 2.5	$ 291.0	$ 40.0
Guarantees issued on behalf of less than wholly-owned consolidated entities	50
Guarantees that expire between 2012 and 2028	330
Guarantees, Performance risk percentage agreed by buyer		100.00%
Guarantees, other risk up to an aggregate maximum amount agreed by buyer		50.00%
Charge recorded		2.5		26.0
Face value of guarantees	$ 19		$ 18	$ 70