Organization and Basis of Presentation (Schedule of New Accounting Pronouncements) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	$ 47,951	$ 51,240	$ 49,545	$ 49,184	$ 47,295	$ 46,611
Accounting Standards Update [Extensible List]	ASU 2016-13
Progress Energy
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	$ 15,593	16,882	16,942	16,241	16,429	16,221
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	4,108	3,293	2,687	2,471	3,260	2,707
Retained Earnings | Progress Energy
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	6,465	$ 7,743	$ 7,809	$ 7,109	$ 7,296	$ 7,090
Cumulative Change in Accounting Principle | Retained Earnings | Revision of Prior Period, Accounting Standards Update, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	120
Cumulative Change in Accounting Principle | Retained Earnings | Revision of Prior Period, Accounting Standards Update, Adjustment | Duke Energy Carolinas
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	16
Cumulative Change in Accounting Principle | Retained Earnings | Revision of Prior Period, Accounting Standards Update, Adjustment | Progress Energy
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	2
Cumulative Change in Accounting Principle | Retained Earnings | Revision of Prior Period, Accounting Standards Update, Adjustment | Duke Energy Progress
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	1
Cumulative Change in Accounting Principle | Retained Earnings | Revision of Prior Period, Accounting Standards Update, Adjustment | Duke Energy Florida
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	1
Cumulative Change in Accounting Principle | Retained Earnings | Revision of Prior Period, Accounting Standards Update, Adjustment | Piedmont
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total pretax impact to Retained Earnings	$ 1