Fair Value Measurements (Details Textuals) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fair Value of Financial Instruments [Line Items]
Investment excludes receivables, payables and accrued income	$ (3)	$ 7
Cash balance excluded from available for sale securities	61	157
Investments not required to be disclosed	266	255
FES
Fair Value of Financial Instruments [Line Items]
Investment excludes receivables, payables and accrued income	2	1
Cash balance excluded from available for sale securities	$ 44	$ 139