Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of Recurring Fair Value Measurements

Recurring Fair Value Measures

	As of Dec. 31, 2015
(millions)	Level 1		Level 2		Level 3		Total
Assets
Natural gas derivatives	$	0.0	$	0.2	$	0.0	$	0.2
Liabilities
Natural gas derivatives	$	0.0	$	26.2	$	0.0	$	26.2
	As of Dec. 31, 2014
(millions)	Level 1		Level 2		Level 3		Total
Liabilities
Natural gas derivatives	$	0.0	$	42.7	$	0.0	$	42.7

Tampa Electric Company [Member]

Schedule of Recurring Fair Value Measurements

Recurring Derivative Fair Value Measures

	As of Dec. 31, 2015
(millions)	Level 1		Level 2		Level 3		Total
Liabilities
Natural gas swaps	$	0.0	$	26.2	$	0.0	$	26.2
	As of Dec. 31, 2014
(millions)	Level 1		Level 2		Level 3		Total
Liabilities
Natural gas swaps	$	0.0	$	42.7	$	0.0	$	42.7