Employee Benefit Plans (Target and Actual Asset Allocations) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
VEBA I [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
US Equity Securities [Member] | VEBA I [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	23.00%	20.00%
Target allocation	30.00%
US Equity Securities [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	28.00%	28.00%
Target allocation	28.00%
US Equity Securities [Member] | Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	20.00%	28.00%
Target allocation	29.00%
Non US Equity Securities [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	15.00%	15.00%
Target allocation	15.00%
Non US Equity Securities [Member] | Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	14.00%	15.00%
Target allocation	19.00%
Global Equity Securities [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	10.00%	9.00%
Target allocation	10.00%
Global Equity Securities [Member] | Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	8.00%	9.00%
Target allocation	4.00%
Cash and Cash Equivalents [Member] | VEBA I [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	45.00%	49.00%
Target allocation	25.00%
Debt Securities [Member] | VEBA I [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	32.00%	31.00%
Target allocation	45.00%
Debt Securities [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	32.00%	32.00%
Target allocation	32.00%
Debt Securities [Member] | Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	35.00%	36.00%
Target allocation	35.00%
Global Private Equity Securities [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	3.00%	1.00%
Target allocation	3.00%
Global Private Equity Securities [Member] | Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	10.00%	0.00%
Target allocation	6.00%
Hedge Funds [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	4.00%	3.00%
Target allocation	4.00%
Hedge Funds [Member] | Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	9.00%	6.00%
Target allocation	7.00%
Real Estate [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	4.00%	9.00%
Target allocation	4.00%
Real Estate [Member] | Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	1.00%	6.00%
Target allocation	0.00%
Other Global Securities [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	4.00%	3.00%
Target allocation	4.00%
Other Global Securities [Member] | Master Trust [Member] | Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	3.00%	0.00%
Target allocation	0.00%