Condensed Consolidated Statements of Changes in Equity - Piedmont - USD ($) $ in Millions	Total	Common Stock	Retained Earnings	Total Equity	Noncontrolling Interests	Piedmont	Piedmont Common Stock	Piedmont Retained Earnings	Piedmont Total Equity	Piedmont Noncontrolling Interests
Beginning Balance (Attributable to Parent) at Dec. 31, 2020		$ 1	$ 2,471	$ 47,964			$ 1,310	$ 1,405	$ 2,715
Beginning Balance (Attributable to Noncontrolling Interest) at Dec. 31, 2020					$ 1,220					$ 0
Beginning Balance (Parent) at Dec. 31, 2020	$ 49,184					$ 2,715
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,579					310		310	310
Contribution from parent						325	325		325
Other	(8)			(9)	1	(1)		(1)	(1)
Ending Balance (Attributable to Parent) at Dec. 31, 2021		1	3,265	49,296			1,635	1,714	3,349
Ending Balance (Attributable to Noncontrolling Interest) at Dec. 31, 2021					1,840					0
Ending Balance (Parent) at Dec. 31, 2021	51,136					3,349
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,455					323		323	323
Other	3		1	2	1	1				1
Ending Balance (Attributable to Parent) at Dec. 31, 2022	49,322	1	2,637	49,322		3,672	1,635	2,037	3,672
Ending Balance (Attributable to Noncontrolling Interest) at Dec. 31, 2022	2,531				2,531	1				1
Ending Balance (Parent) at Dec. 31, 2022	51,853					3,673
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,874					379		379	379
Other	(2)		1	(6)	4
Ending Balance (Attributable to Parent) at Dec. 31, 2023	49,112	$ 1	$ 2,235	$ 49,112		4,051	$ 1,635	$ 2,416	$ 4,051
Ending Balance (Attributable to Noncontrolling Interest) at Dec. 31, 2023	1,075				$ 1,075	1				$ 1
Ending Balance (Parent) at Dec. 31, 2023	$ 50,187					$ 4,052