Fair Value Measurements (Additional Fair Value Disclosure) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 40,593	$ 40,256
Long-term debt, fair value	44,558	42,592
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	8,435	8,436
Long-term debt, fair value	9,510	9,123
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	14,518	14,115
Long-term debt, fair value	16,387	15,234
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	5,717	5,235
Long-term debt, fair value	6,045	5,323
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	5,107	4,886
Long-term debt, fair value	5,892	5,408
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	1,784	2,188
Long-term debt, fair value	1,983	2,237
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,795	3,796
Long-term debt, fair value	$ 4,374	$ 4,171