Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 agreement
Guarantees Letters Of Credit [Abstract]
The range of expiration dates of guarantees made by the Parent Company	less than one year to more than 21 years
Lower limit of expiration dates of guarantees (less than one year)	1 year
Upper limit of expiration dates of guarantees (more than 21 years)	21 years
Obligations made by the Parent Company associated with non-recourse debt	$ 24
Contingent Contractual Obligations [Line Items]
Amount	825
Number of agreements	36
Guarantees
Contingent Contractual Obligations [Line Items]
Amount	661
Number of agreements	21
Maximum exposure range for each agreement	<$1 - 280
Maximum exposure range, lower limit (less than $1)	1
Maximum exposure range, upper limit (less than $1 for letters of credit under senior secured credit facility)	280
Cash Collateralized Letters Of Credit
Contingent Contractual Obligations [Line Items]
Amount	163
Number of agreements	12
Maximum exposure range for each agreement	<$1 - 109
Maximum exposure range, lower limit (less than $1)	1
Maximum exposure range, upper limit (less than $1 for letters of credit under senior secured credit facility)	109
Letter of Credit
Contingent Contractual Obligations [Line Items]
Amount	1
Number of agreements	3
Maximum exposure range for each agreement	<$1
Maximum exposure range, upper limit (less than $1 for letters of credit under senior secured credit facility)	$ 1
Letter of Credit | Minimum
Contingent Contractual Obligations [Line Items]
Letter of credit fees paid	0.20%
Letter of Credit | Maximum
Contingent Contractual Obligations [Line Items]
Letter of credit fees paid	3.25%