Related Party Transactions Intercompany Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Duke Energy Carolinas [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	$ 107	$ 75
Due to Related Parties, Current	229	154
Duke Energy Carolinas [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	122	43
Progress Energy [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	375	59
Due to Related Parties, Current	311	203
Progress Energy [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	120	713
Duke Energy Progress [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	16	10
Due to Related Parties, Current	190	120
Duke Energy Progress [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	104	267
Duke Energy Florida [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	84	40
Due to Related Parties, Current	116	70
Duke Energy Florida [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current		174
Due to Related Parties, Current	96
Duke Energy Ohio [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	84	107
Due to Related Parties, Current	53	74
Duke Energy Ohio [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	54	39
Duke Energy Indiana [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	71	115
Due to Related Parties, Current	83	58
Duke Energy Indiana [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current		$ 95
Due to Related Parties, Current	$ 47