Employee Postretirement Benefits - Schedule of Assumptions Used to Determine Benefit (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.118%	4.196%
Rate of compensation increase - weighted	3.73%	3.76%
Healthcare cost trend rate
Immediate rate
Ultimate rate
Year rate reaches ultimate
Pension Benefits [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.118%	4.196%
Rate of compensation increase - weighted	3.73%	3.76%
Healthcare cost trend rate
Immediate rate
Ultimate rate
Year rate reaches ultimate
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.096%	4.18%
Rate of compensation increase - weighted	3.71%	3.74%
Healthcare cost trend rate
Immediate rate	7.25%	7.50%
Ultimate rate	4.50%	4.50%
Year rate reaches ultimate	2025	2025
Other Postretirement Benefits [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.096%	4.18%
Rate of compensation increase - weighted	3.71%	3.74%
Healthcare cost trend rate
Immediate rate	7.25%	7.50%
Ultimate rate	4.50%	4.50%
Year rate reaches ultimate	2025	2025
Net Periodic Benefit Cost [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.196%	4.797%	5.30%
Expected long-term return on plan assets	7.50%	7.50%	7.75%
Rate of compensation increase	3.76%	3.83%	3.88%
Healthcare cost trend rate
Immediate rate
Ultimate rate
Year rate reaches ultimate
Net Periodic Benefit Cost [Member] | Pension Benefits [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.196%	4.797%	5.30%
Expected long-term return on plan assets	7.50%	7.50%	7.75%
Rate of compensation increase	3.76%	3.83%	3.88%
Healthcare cost trend rate
Immediate rate
Ultimate rate
Year rate reaches ultimate
Net Periodic Benefit Cost [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.18%	4.744%	5.25%
Expected long-term return on plan assets
Rate of compensation increase	3.74%	3.82%	3.87%
Healthcare cost trend rate
Immediate rate	7.50%	7.75%	8.00%
Ultimate rate	4.50%	4.50%	4.50%
Year rate reaches ultimate	2025	2025	2023
Net Periodic Benefit Cost [Member] | Other Postretirement Benefits [Member] | Tampa Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.18%	4.744%	5.25%
Rate of compensation increase	3.74%	3.82%	3.87%
Healthcare cost trend rate
Immediate rate	7.50%	7.75%	8.00%
Ultimate rate	4.50%	4.50%	4.50%
Year rate reaches ultimate	2025	2025	2023