Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 185.2	$ 200.5
Receivables, less allowance for uncollectibles	287.2	282.7
Inventories, at average cost
Derivative assets	9.7	0
Regulatory assets	34.3	70.3
Deferred income taxes	100.3	63.3
Prepayments and other current assets	34.9	33.9
Income tax receivables	1.5	0.4
Total current assets	857.7	856.8
Property, plant and equipment
Construction work in progress	386.7	336.1
Other property	448.3	443.8
Property, plant and equipment, at original costs	9,077.3	8,664.0
Accumulated depreciation	(2,907.2)	(2,695.5)
Total property, plant and equipment, net	6,170.1	5,968.5
Other assets
Regulatory assets	293.1	382.6
Derivative assets	0.3	0.2
Deferred charges and other assets	126.8	126.8
Total other assets	420.2	509.6
Total assets	7,448.0	7,334.9
Current liabilities
Long-term debt due within one year	83.3	0
Notes payable	84.0	0
Accounts payable	261.7	232.8
Customer deposits	164.5	162.9
Regulatory liabilities	85.8	105.6
Derivative liabilities	0.1	14.6
Interest accrued	31.9	33.2
Taxes accrued	34.6	32.1
Other	19.5	19.9
Total current liabilities	765.4	601.1
Other liabilities
Deferred income taxes	444.0	277.9
Investment tax credits	9.4	9.7
Regulatory liabilities	631.4	631.4
Derivative liabilities	0.2	0.6
Deferred credits and other liabilities	426.1	549.7
Long-term debt, less amount due within one year	2,837.8	2,972.7
Total other liabilities	4,348.9	4,442.0
Commitments and Contingencies
Capital
Common equity	217.3	216.6
Additional paid in capital	1,581.3	1,564.5
Retained earnings	548.3	541.7
Accumulated other comprehensive loss	(13.2)	(31.0)
Total capital	2,333.7	2,291.8
Total liabilities and capital	7,448.0	7,334.9
Fuel [Member]
Inventories, at average cost
Utility inventories	118.7	123.6
Materials and Supplies [Member]
Inventories, at average cost
Utility inventories	85.9	82.1
Electric [Member]
Property, plant and equipment
Electric	6,934.0	6,655.8
Gas [Member]
Property, plant and equipment
Electric	1,308.3	1,228.3
Tampa Electric Company [Member]
Current assets
Cash and cash equivalents	9.8	45.2
Receivables, less allowance for uncollectibles	227.6	213.8
Inventories, at average cost
Derivative assets	9.5	0
Regulatory assets	34.3	70.3
Deferred income taxes	29.4	20.0
Prepayments and other current assets	12.5	11.5
Income tax receivables	54.9	22.1
Total current assets	548.5	544.4
Property, plant and equipment
Construction work in progress	385.3	335.0
Property, plant and equipment, at original costs	8,568.8	8,161.4
Accumulated depreciation	(2,562.6)	(2,373.6)
Public utilities, property, plant and equipment, net	6,006.2	5,787.8
Other property	8.3	7.3
Total property, plant and equipment, net	6,014.5	5,795.1
Other assets
Unamortized debt expense	14.8	16.1
Regulatory assets	293.1	382.6
Derivative assets	0.3	0.2
Other	4.6	6.2
Total other assets	312.8	405.1
Total assets	6,875.8	6,744.6
Current liabilities
Long-term debt due within one year	83.3	0
Notes payable	84.0	0
Accounts payable	226.0	188.6
Customer deposits	164.5	163.0
Regulatory liabilities	85.8	105.6
Derivative liabilities	0	14.1
Interest accrued	16.4	17.3
Taxes accrued	12.2	13.7
Other	12.0	11.8
Total current liabilities	684.2	514.1
Other liabilities
Deferred income taxes	1,114.3	980.9
Investment tax credits	9.4	9.7
Regulatory liabilities	631.4	631.4
Derivative liabilities	0.2	0.2
Other	308.1	409.4
Long-term debt, less amount due within one year	1,797.5	1,932.6
Total other liabilities	2,063.4	2,031.6
Commitments and Contingencies
Capital
Common equity	2,030.4	1,970.4
Retained earnings	308.1	304.6
Accumulated other comprehensive loss	(7.8)	(8.7)
Total capital	2,330.7	2,266.3
Total capitalization	4,128.2	4,198.9
Total liabilities and capital	6,857.8	6,744.6
Tampa Electric Company [Member] | Fuel [Member]
Inventories, at average cost
Utility inventories	93.7	89.1
Tampa Electric Company [Member] | Materials and Supplies [Member]
Inventories, at average cost
Utility inventories	76.8	72.4
Tampa Electric Company [Member] | Electric [Member]
Property, plant and equipment
Electric	6,934.0	6,654.5
Tampa Electric Company [Member] | Gas [Member]
Property, plant and equipment
Electric	$ 1,249.5	$ 1,171.9