XML 66 R54.htm IDEA: XBRL DOCUMENT v3.5.0.2
Fair Value Measurements (Details Textuals) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Fair Value of Financial Instruments [Line Items]    
Investment excludes receivables, payables and accrued income $ 7 $ 7
Cash balance excluded from available for sale securities 176 157
Investments not required to be disclosed $ 273 255
NUG contracts    
Fair Value of Financial Instruments [Line Items]    
Period of future observable data to determine contract price 3 years  
FES    
Fair Value of Financial Instruments [Line Items]    
Investment excludes receivables, payables and accrued income $ 4 1
Cash balance excluded from available for sale securities $ 154 $ 139