Variable Interest Entities (Schedule of Non-Consolidated VIE Pipeline Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,936	$ 1,409	$ 1,175
VIE, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,479	1,060
ACP | VIE, Not Primary Beneficiary
Variable Interest Entity [Line Items]
VIE Ownership interest	47.00%
Investments in equity method unconsolidated affiliates	$ 1,179	797
Constitution | VIE, Not Primary Beneficiary
Variable Interest Entity [Line Items]
VIE Ownership interest	24.00%
Investments in equity method unconsolidated affiliates		25
Pipeline Investments | VIE, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,179	822
Gas Utilities and Infrastructure
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	1,388	1,003	$ 763
Gas Utilities and Infrastructure | Constitution | VIE, Not Primary Beneficiary
Variable Interest Entity [Line Items]
OTTI impairment loss	$ 25	$ 55