Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 386		$ 390
Investments and other assets	3,251		3,432
Other current liabilities	1,612		1,996
Deferred credits and other liabilities	26,511		26,575
Long-term debt	39,885				40,256
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	155		213
Intangibles			96
Investments and other assets	4		4
Total assets	159		313
Other current liabilities	2		3
Deferred credits and other liabilities	14		15
Total liabilities	16		18
Net assets (liabilities)	143		295
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	152		153
Total assets	152		153
Net assets (liabilities)	152		153
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	3		60
Intangibles			96
Investments and other assets	4		4
Total assets	7		160
Other current liabilities	2		3
Deferred credits and other liabilities	14		15
Total liabilities	16		18
Net assets (liabilities)	(9)		142
Duke Energy Carolinas [Member]
Variable Interest Entities [Line Items]
Investments and other assets	994		1,000
Other current liabilities	348		393
Deferred credits and other liabilities	10,978		10,923
Long-term debt	8,436				8,436
Progress Energy [Member]
Variable Interest Entities [Line Items]
Investments and other assets	767		804
Other current liabilities	747		896
Deferred credits and other liabilities	9,906		9,429
Long-term debt	15,046				14,115
Duke Energy Progress [Member]
Variable Interest Entities [Line Items]
Investments and other assets	459		443
Other current liabilities	329		392
Deferred credits and other liabilities	6,736		6,502
Long-term debt	5,717				5,235
Duke Energy Florida [Member]
Variable Interest Entities [Line Items]
Investments and other assets	252		252
Other current liabilities	406		445
Deferred credits and other liabilities	3,813		3,821
Long-term debt	5,110				4,886
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Investments and other assets	34		232
Other current liabilities	72		110
Deferred credits and other liabilities	2,066		2,546
Long-term debt	2,187				2,188
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables	127		114	[1]
Intangibles			96	[1]
Total assets	127		210	[1]
Net assets (liabilities)	127		210	[1]
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Investments and other assets	215		269
Other current liabilities	84		88
Deferred credits and other liabilities	2,294		2,334
Long-term debt	3,796				3,796
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables	134	[2]	143	[3]
Total assets	134	[2]	143	[3]
Net assets (liabilities)	$ 134	[2]	$ 143	[3]

[1] Reflects OVEC and retained interest in CRC.

[2] Reflects retained interest in CRC.

[3] Reflects retained interest in CRC