Debt (Letter of Credit) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 675		$ 630
Corporate Revolving Facility [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	235	[1]	242	[1]
CDH [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	269	[2]	218	[2]
Various Project Financing Facilities [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 171		$ 170

[1] The Corporate Revolving Facility represents our primary revolving facility. On July 30, 2014, we amended our Corporate Revolving Facility to increase the capacity by an additional $500 million to $1.5 billion.

[2] During the first quarter of 2014, we amended our CDHI letter of credit facility to lower our fees and extend the maturity to January 2, 2018.