Debt (Letter of Credit) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 649		$ 630
Corporate Revolving Facility [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	239	[1]	242	[1]
CDH [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	240		218
Various Project Financing Facilities [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 170		$ 170

[1] The Corporate Revolving Facility represents our primary revolving facility.