Summary of Significant Accounting and Reporting Policies (Goodwill and Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets [Line Items]
Goodwill	$ 891	$ 764
Other intangible assets not subject to amortization, primarily land easements	135	138
Other intangible assets:
Total	659	1,300
Accumulated amortization	(86)	(151)
Total other intangible assets subject to amortization - net	573	1,149
Intangible assets, amortization [Abstract]
Amortization expense	19	35	$ 35
Amortization Expense 2019	25
Amortization Expense 2020	26
Amortization Expense 2021	24
Amortization Expense 2022	21
Amortization Expense 2023	$ 21
Customer relationships associated with gas infrastructure [Member]
Other intangible assets:
Weighted average useful lives (years)	41 years
Total	$ 0	700
Purchased Power Agreements [Member]
Other intangible assets:
Weighted average useful lives (years)	21 years
Total	$ 625	521
Other, primarily transmission and development rights and customer lists [Member]
Other intangible assets:
Weighted average useful lives (years)	22 years
Total	$ 34	79
FPL[Member]
Goodwill and Intangible Assets [Line Items]
Goodwill	304	11
Gas Infrastructure, primarily Texas pipelines [Member]
Goodwill and Intangible Assets [Line Items]
Goodwill	487	641
Customer Supply [Member]
Goodwill and Intangible Assets [Line Items]
Goodwill	72	72
Generation Assets [Member]
Goodwill and Intangible Assets [Line Items]
Goodwill	$ 28	$ 40