Discontinued Operations (Significant Non-cash Items and Capital Expenditures) (Details) - DT Midstream - Discontinued operations, spinoff $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($)
Operating Activities
Depreciation and amortization	$ 82
Deferred income taxes	54
Equity earnings of equity method investees	(59)
Asset (gains) losses and impairments, net	19
Investing Activities
Plant and equipment expenditures — non-utility	$ (60)