Debt and Credit Facilities - Debt and Credit Facilities (Details) (USD $) In Millions, unless otherwise specified			12 Months Ended			1 Months Ended	12 Months Ended				12 Months Ended					12 Months Ended		12 Months Ended				12 Months Ended									12 Months Ended		12 Months Ended				12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Parent	Dec. 31, 2010 Parent	Dec. 31, 2010 Parent Series A Floating Rate Notes	Jan. 31, 2011 Parent Senior Notes	Dec. 31, 2009 Parent Senior Notes	Dec. 31, 2011 Parent Senior Notes Due March 1, 2011	Dec. 31, 2011 Parent Senior unsecured notes	Dec. 31, 2010 Parent Senior unsecured notes	Dec. 31, 2011 PEC	Dec. 31, 2010 PEC	Dec. 31, 2011 PEC First Mortgage Bonds Due September 15, 2021	Dec. 31, 2011 PEC First mortgage bonds	Dec. 31, 2010 PEC First mortgage bonds	Dec. 31, 2011 PEC Pollution control obligations	Dec. 31, 2010 PEC Pollution control obligations	Dec. 31, 2011 PEC Senior unsecured notes	Dec. 31, 2010 PEC Senior unsecured notes	Dec. 31, 2011 PEC Miscellaneous notes	Dec. 31, 2010 PEC Miscellaneous notes	Dec. 31, 2011 PEF	Dec. 31, 2010 PEF	Dec. 31, 2010 PEF First Mortgage Bonds Due June 1, 2010	Dec. 31, 2011 PEF First Mortgage Bonds Due July 15, 2011	Dec. 31, 2010 PEF First Mortgage Bonds Due 2020	Dec. 31, 2011 PEF First Mortgage Bonds Due August 15, 2021	Dec. 31, 2010 PEF First Mortgage Bonds Due 2040	Dec. 31, 2011 PEF First mortgage bonds	Dec. 31, 2010 PEF First mortgage bonds	Dec. 31, 2011 PEF Pollution control obligations	Dec. 31, 2010 PEF Pollution control obligations	Dec. 31, 2011 PEF Medium-term notes	Dec. 31, 2010 PEF Medium-term notes	Dec. 31, 2011 Florida Progress Funding Corporation	Dec. 31, 2010 Florida Progress Funding Corporation	Dec. 31, 2011 Florida Progress Funding Corporation Debt to affiliated trust	Dec. 31, 2010 Florida Progress Funding Corporation Debt to affiliated trust
Long-term debt [Line Items]
Debt instrument, face amount						$ 500			$ 4,000	$ 4,200			$ 500	$ 3,025	$ 2,525	$ 669	$ 669	$ 500	$ 500	$ 5	$ 5					$ 250	$ 300	$ 350	$ 4,100	$ 4,100	$ 241	$ 241	$ 150	$ 150			$ 309	$ 309
Weighted-average interest rates									6.28%					5.17%		0.57%		6.50%		6.00%									5.56%		0.57%		6.75%				7.10%
Maturity date - range start									2012					2013		2017		2012											2013		2018		2028				2039
Maturity date - range end									2039					2038		2024		2012											2040		2027		2028				2039
Maturity date					Jan. 15, 2010	Jan. 15, 2021		Mar. 01, 2011					Sep. 15, 2021											Jun. 01, 2010	Jul. 15, 2011	Apr. 01, 2020	Aug. 15, 2021	Apr. 01, 2040
Unamortized premium and discount, net			(7)	(6)							(6)	(6)										(9)	(9)												(36)	(36)
Current portion of long-term debt	(950)	(505)	(450)	(205)							(500)	0										0	(300)
Long-term debt, net	11,718	11,864	3,543	3,989							3,693	3,693										4,482	4,182
Long-term debt, affiliate	273	273																																	273	273
Maturities of debt					100			700																300	300
Proceeds from issuance of debt						495	950
Debt instrument issuance date						January 21, 2011	November 19, 2009						September 15, 2011													March 25, 2010	August 18, 2011	March 25, 2010
Debt instrument, interest rate stated percentage						4.40%		7.10%					3.00%											4.50%	6.65%	4.55%	3.10%	5.65%
RCAs and available capacity [Line Items]
RCA term			Five-year	Five-year							Three-year	Three-year										Three-year	Three-year
RCA expiration date			5/3/12	5/3/12							10/15/13	10/15/13										10/15/13	10/15/13
RCA total	1,978	2,000	478	500							750	750										750	750
RCA outstanding	0	0	0	0							0	0										0	0
RCA reserved	669	31	252	31							184	0										233	0
RCA available	1,309	1,969	226	469							566	750										517	750
Supplemental data
RCA letters of credit			2	31
Short Term Debt [Line Items]
Weighted-average interest rates	0.50%	0.00%	0.50%	0.00%							0.49%	0.00%										0.51%	0.00%
Short-term debt	671	0	250	0							188	0										233	0
Maturities Of Long Term Debt [Line Items]
2012	950
2013	830
2014	300
2015	1,000
2016	$ 300