XML 123 R105.htm IDEA: XBRL DOCUMENT v3.6.0.2
Fair Value Measurements (Details 3) - USD ($)
$ in Millions
Dec. 31, 2016
Dec. 31, 2015
Debt securities    
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities    
Cost Basis $ 1,735 $ 1,778
Unrealized Gains 38 16
Fair Value 1,773 1,794
Equity securities    
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities    
Cost Basis 822 542
Unrealized Gains 103 34
Fair Value 925 576
FES | Debt securities    
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities    
Cost Basis 847 801
Unrealized Gains 27 9
Fair Value 874 810
FES | Equity securities    
Amortized cost basis, unrealized gains and losses and fair values of investments in available-for-sale securities    
Cost Basis 564 354
Unrealized Gains 70 24
Fair Value $ 634 $ 378