Employee Postretirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Primary provisions for pension benefits	First, for plans funded less than 100%, required shortfall contributions will be based on a percentage of the funding target until 2012, rather than the funding target of 100%.
Percentage of qualified pension plan's actuarial value of assets		96.70%
Estimated percentage of qualified pension plan's actuarial value of assets	98.20%
Percentage of tax-free subsidy under prescription drug programs	28.00%
Amortization period of Regulatory Asset	12 years
Tax of premiums paid for retiree medical benefits plan	40.00%
Accumulated benefit obligation of defined benefit pension plans	$ 624.1	$ 664.7
Percentage of defined benefit plan actual return on plan assets	12.00%
Employer contributions	42.0	35.5
Employer contributions in next fiscal year	47.5
Defined contribution plan, maximum employer match percentage	6.00%
Description of defined contribution plan	Employer matching contributions were 65% of eligible participant contributions with additional incentive match of up to 35% of eligible participant contributions based on the achievement of certain operating company financial goals. Prior to this, the employer matching contributions were 60% of eligible participant contributions, with an additional incentive match of up to 40%.
Defined contribution plan cost recognized	11.3	7.0	9.0
Employer matching contribution percentage of eligible participant contribution	60.00%
Defined benefit plan additional percentage of eligible compensation for matching contributions by employer	40.00%
Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of qualified pension plan's actuarial value of assets		96.70%
Estimated percentage of qualified pension plan's actuarial value of assets	98.20%
Percentage of tax-free subsidy under prescription drug programs	28.00%
Tax of premiums paid for retiree medical benefits plan	40.00%
Employer contributions	33.5	27.9
Employer contributions in next fiscal year	38.4
Defined contribution plan cost recognized	9.1	6.0	5.8
TECO Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of defined benefit plan actual return on plan assets	12.00%
TECO Coal [Member]
Defined Benefit Plan Disclosure [Line Items]
Black lung liability	24.5	27.1
Expenses related to black lung liability	2.2	1.8	1.7
Pre Amendment [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution percentage of eligible participant contribution	60.00%
Defined benefit plan additional percentage of eligible compensation for matching contributions by employer	40.00%
Post Amendment [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution percentage of eligible participant contribution	65.00%
Defined benefit plan additional percentage of eligible compensation for matching contributions by employer	35.00%
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of estimated annual contributions	4.0
Minimum [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of estimated annual contributions	3.0
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of estimated annual contributions	48.0
Maximum [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Range of estimated annual contributions	39.0
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation for other postretirement benefits	666.0	715.0	646.4
Estimated net loss amortization from AOCI into net periodic benefit cost related to defined benefit plan	2.5
Estimated Prior service cost amortization from AOCI into net periodic benefit cost related to defined benefit plan	0.1
Defined benefit plan net loss that will be amortized from regulatory assets in next fiscal year	10.5
Defined benefit plan prior service benefit that will be amortized from regulatory assets in next fiscal year	0.5
Employer contributions	45.9	36.8
Net periodic benefit cost	29.8	24.9	20.3
Pension Benefits [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan net loss that will be amortized from regulatory assets in next fiscal year	10.5
Defined benefit plan prior service benefit that will be amortized from regulatory assets in next fiscal year	0.5
Net periodic benefit cost	21.7	18.3	13.1
Pension Benefits [Member] | TECO Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation for other postretirement benefits	666.0	715.0	646.4
Employer contributions	45.9	36.8
Net periodic benefit cost	29.8	24.9	20.3
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation for other postretirement benefits	208.1	230.3	216.5
Estimated Prior service cost amortization from AOCI into net periodic benefit cost related to defined benefit plan	0.2
Other postretirement benefit plans, Net loss that will be amortized from regulatory assets in next fiscal year	0
Employer contributions	11.9	9.8
Employer contributions in next fiscal year	13.3
Net periodic benefit cost	12.4	15.2	16.4
Other Postretirement Benefits [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Other postretirement benefit plans, Net loss that will be amortized from regulatory assets in next fiscal year	0
Employer contributions in next fiscal year	10.8
Net periodic benefit cost	10.0	12.4	10.0
Other Postretirement Benefits [Member] | TECO Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation for other postretirement benefits	208.1	230.3	216.5
Employer contributions	11.9	9.8
Net periodic benefit cost	12.4	15.2	16.4
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	2.6	1.3
Employer contributions in next fiscal year	3.3
SERP [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	1.0	0.6
Employer contributions in next fiscal year	$ 0.9