Condensed Consolidated Statements Of Common Stockholder's Equity - Indiana (USD $) In Millions	Total	Retained Earnings [Member]	Net Gains (Losses) on Cash Flow Hedges [Member]	Pension And OPEB Related Adjustments To AOCI [Member]	Duke Energy Indiana [Member]	Duke Energy Indiana [Member] Common Stock [Member]	Duke Energy Indiana [Member] Additional Paid In Capital [Member]	Duke Energy Indiana [Member] Retained Earnings [Member]	Duke Energy Indiana [Member] Net Gains (Losses) on Cash Flow Hedges [Member]
Balance at Dec. 31, 2010			$ 8		$ 3,567	$ 1	$ 1,358	$ 2,200
Net income	954	946			144			144
Other comprehensive income, net of tax	90		(3)	(7)
Transfer of Vermillion Generating Station					0
Balance at Jun. 30, 2011					3,711	1	1,358	2,344	8
Balance at Mar. 31, 2011
Net income	441				68
Other comprehensive income, net of tax	62
Balance at Jun. 30, 2011					3,711	1	1,358		8
Balance at Dec. 31, 2011	22,772				3,734	1	1,358	2,368	7
Net income	747	739			(90)			(90)
Other comprehensive income, net of tax	(90)		(15)	6	(1)				(1)
Transfer of Vermillion Generating Station					26
Balance at Jun. 30, 2012	22,419				3,669	1	1,384	2,278	6
Balance at Mar. 31, 2012
Net income	448				77
Other comprehensive income, net of tax	(150)
Balance at Jun. 30, 2012	$ 22,419				$ 3,669	$ 1	$ 1,384