Property, Plant and Equipment (Regulated and Non-Regulated Generation and Distribution PP&E) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	$ 28,539	$ 27,282
Accumulated depreciation	(9,528)	(8,939)
Net electric generation and distribution assets and other	19,011	18,343
Regulated Operation [Member]
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	11,021	10,789
Accumulated depreciation	(4,194)	(3,984)
Net electric generation and distribution assets and other	6,827	6,805
Unregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Electric generation, distribution assets and other	17,518	16,493
Accumulated depreciation	(5,334)	(4,955)
Net electric generation and distribution assets and other	$ 12,184	$ 11,538