Investments In Debt And Equity Securities (Tables)

12 Months Ended

Dec. 31, 2011

Investments In Debt And Equity Securities [Abstract]

Available-For-Sale Investments

	December 31, 2011							December 31, 2010
	Gross Unrealized Holding Gains(a)		Gross Unrealized Holding Losses(a)			Estimated Fair Value		Gross Unrealized Holding Gains(a)		Gross Unrealized Holding Losses(a)			Estimated Fair Value
Short-term Investments	$	—	$	—		$	190	$	—	$	—		$	—
Total short-term investments	$	—	$	—		$	190	$	—	$	—		$	—
Equity Securities	$	448	$	(18	)	$	1,397	$	481	$	(16	)	$	1,435
Corporate Debt Securities		9		(3	)		256		12		(3	)		270
Municipal Bonds		3		—			79		1		(9	)		69
U.S. Government Bonds		17		—			327		10		(1	)		235
Auction Rate Debt Securities		—		(17	)		71		—		(31	)		118
Other		6		(4	)		229		11		(5	)		274
Total long-term investments	$	483	$	(42	)	$	2,359	$	515	$	(65	)	$	2,401

(a) The table above includes unrealized gains and losses of $473 million and $22 million, respectively, at December 31, 2011 and unrealized gains and losses of $505 million and $32 million, respectively, at December 31, 2010 associated with investments held in the Duke Energy Carolinas NDTF. Additionally, the table above includes unrealized gains of $6 million and $1 million of unrealized losses at December 31, 2011, and unrealized gains of $6 million and an insignificant amount of unrealized losses, at December 31, 2010 associated with investments held in the Duke Energy Indiana grantor trust. As discussed above, unrealized losses on investments within the NDTF and Duke Energy Indiana grantor trust are deferred as a regulatory asset pursuant to regulatory accounting treatment.

Unrealized Losses Of Available-For-Sale Debt And Equity Securities In A Continuous Loss Position

	As of December 31, 2011								As of December 31, 2010
	Estimated Fair Value(a)		Unrealized Loss Position >12 months			Unrealized Loss Position <12 months			Estimated Fair Value(a)		Unrealized Loss Position >12 months			Unrealized Loss Position <12 months
Equity Securities	$	123		(6	)	$	(12	)	$	85		(11	)	$	(5	)
Corporate Debt Securities		258		(2	)		(1	)		73		(2	)		(2	)
Municipal Bonds		3		—			—			42		(8	)		(1	)
U.S. Government Bonds		8		—			—			38		—			(1	)
Auction Rate Debt Securities(b)		71		(17	)		—			118		(31	)		—
Other		121		—			(4	)		84		(1	)		(3	)
Total long-term investments	$	584	$	(25	)	$	(17	)	$	440	$	(53	)	$	(12	)

(a) The table above includes fair values of $289 million and $226 million at December 31, 2011 and December 31, 2010, respectively, associated with investments held in the Duke Energy Carolinas NDTF. Additionally, the table above includes fair values of $11 million and $5 million at December 31, 2011 and December 31, 2010, respectively, associated with investments held in the Duke Energy Indiana grantor trust.

(b) See Note 15 for information about fair value measurements related to investments in auction rate debt securities.