Investments in Unconsolidated Affiliates (Investments in Equity Method Unconsolidated Affiliates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,936	$ 1,409	$ 1,175
Equity in earnings of unconsolidated affiliates	162	83	119
Electric Utilities and Infrastructure
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	122	97	89
Equity in earnings of unconsolidated affiliates	9	6	5
Gas Utilities and Infrastructure
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	1,388	1,003	763
Equity in earnings of unconsolidated affiliates	114	27	62
Commercial Renewables
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	314	201	190
Equity in earnings of unconsolidated affiliates	(4)	(1)	(5)
Other
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	112	108	133
Equity in earnings of unconsolidated affiliates	$ 43	$ 51	$ 57