Schedule I - Condensed Parent Company Financial Statements (Balance Sheets) (Details) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Condensed Financial Statements, Captions
Cash and cash equivalents	$ 1,424		$ 2,110		$ 1,670	$ 1,542
Short Term Investments	333		190
Receivables (net of allowance for doubtful accounts)	1,516		784
OtherAssetsCurrent	2,425		1,051
Total current assets	10,122		6,880
Notes receivable	71		62
Investment in consolidated subsidiaries	483		460
Other Assets, Noncurrent	2,399		2,231
Total investments and other assets	23,994		9,160
Total Assets	113,856		62,526		59,090
Accounts Payable, Current	2,444		1,433
Notes payable and commercial paper	745		154
Current maturities of long-term debt	3,110		1,894
Other Liabilities, Current	2,511		1,091
Total current liabilities	10,029		5,528
Long-term Debt Noncurrent	35,499		17,730
Non-current deferred tax liabilities	10,490		7,581
Commitments and Contingencies
Common Stock	1		1
Additional Paid in Capital, Common Stock	39,279		21,132
Retained Earnings (Accumulated Deficit)	1,889		1,873
Accumulated Other Comprehensive Income (Loss), Net of Tax	(306)		(234)
Total Duke Energy Corporation shareholders' equity	40,863		22,772
Total Liabilities and Equity	113,856		62,526
Common stock, par value	$ 0.001
Common stock, shares authorized	2,000,000,000		2,000,000,000
Common stock, shares outstanding	704,000,000		445,000,000		443,000,000	436,000,000
Parent Company [Member]
Condensed Financial Statements, Captions
Cash and cash equivalents	267		845		488	365
Receivables (net of allowance for doubtful accounts)	17		6
Receivables from affiliated companies	128		39
Notes receivable from affiliated companies	1,590		608
OtherAssetsCurrent	191		100
Total current assets	2,193		1,598
Notes Receivable, Related Parties, Noncurrent	450		450
Investment in consolidated subsidiaries	45,048		25,670
Other Assets, Noncurrent	612		571
Total investments and other assets	46,110		26,691
Total Assets	48,303		28,289
Accounts Payable, Current	3		0
Accounts payable to affiliated companies	12		0
Notes payable and commercial paper	745		154
Accrued Income Taxes, Current	12		35
Current maturities of long-term debt	256		0
Other Liabilities, Current	171		65
Total current liabilities	1,199		254
Long-term Debt Noncurrent	5,250		4,223
Notes Payable, Related Parties, Noncurrent	105	[1]	105	[1]
Non-current deferred tax liabilities			16
OtherLiabilitiesNoncurrent	886		919
Total Deferred Credits And Other Liabilities	886		935
Commitments and Contingencies
Common Stock	1		1
Additional Paid in Capital, Common Stock	39,279		21,132
Retained Earnings (Accumulated Deficit)	1,889		1,873
Accumulated Other Comprehensive Income (Loss), Net of Tax	(306)		(234)
Total Duke Energy Corporation shareholders' equity	40,863		22,772
Total Liabilities and Equity	$ 48,303		$ 28,289
Common stock, par value	$ 0.001
Common stock, shares authorized	2,000,000,000
Common stock, shares outstanding	704,000,000		445,000,000

[1] This amount represents an intercompany loan with Duke Energy's affiliate, Bison Insurance Company Limited.