XML 107 R63.htm IDEA: XBRL DOCUMENT v3.5.0.2
Fair Value Measurements and Credit Concentration (Financial Instruments Not Recorded at Fair Value and Credit Concentration) (Details)
$ in Millions
Jun. 30, 2016
USD ($)
counterparty
Dec. 31, 2015
USD ($)
Credit Concentration Associated with Financial Instruments (Numeric) [Abstract]    
Gross credit exposure from energy trading partners $ 425  
Net credit exposure to energy trading partners 265  
Dollar exposure to top ten energy trading counterparties $ 124  
Percentage exposure to top ten energy trading counterparties 47.00%  
Number of counterparties in top ten that have investment grade credit rating | counterparty 8  
Percentage of top ten's exposure that consists of counterparties with investment grade credit rating 88.00%  
Carrying Amount    
Fair Value of Financial Instruments Not Recorded at Fair Value - Other    
Long-term debt $ 3,901 $ 4,186
Fair Value    
Fair Value of Financial Instruments Not Recorded at Fair Value - Other    
Long-term debt $ 3,458 $ 3,343