Quarterly Data - Schedule of Financial Data by Quarter (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Data [Line Items]
Revenues	$ 688.4	$ 765.9	$ 735.9	$ 661.1	$ 688.4	$ 858.6	$ 752.5	$ 697.1	$ 2,851.3	$ 2,996.6	$ 3,209.9
Income from operations	99.6	140.5	119.5	104.1	109.5	183.1	149.1	114.8	463.7	556.5	583.2
Net income from continuing operations	42.1	62.9	51.6	41.2	45.6	90.2	65.6	44.6	197.8	246.0	250.8
Net income attributable to TECO Energy	$ 42.0	$ 62.8	$ 51.4	$ 41.5	$ 45.1	$ 44.0	$ 73.1	$ 50.5	$ 197.7	$ 212.7	$ 272.6
EPS - Basic
From continuing operations	$ 0.20	$ 0.29	$ 0.24	$ 0.19	$ 0.21	$ 0.42	$ 0.30	$ 0.21	$ 0.92	$ 1.14	$ 1.17
Attributable to TECO Energy									$ 0.92	$ 0.99	$ 1.27
EPS - Diluted
From continuing operations	$ 0.20	$ 0.29	$ 0.24	$ 0.19	$ 0.21	$ 0.42	$ 0.30	$ 0.20	$ 0.92	$ 1.14	$ 1.17
Attributable to TECO Energy									$ 0.92	$ 0.99	$ 1.27
Dividends paid per common share outstanding	$ 0.220	$ 0.220	$ 0.220	$ 0.220	$ 0.220	$ 0.220	$ 0.220	$ 0.220	$ 0.88	$ 0.88	$ 0.85
TECO Energy [Member]
EPS - Basic
Attributable to TECO Energy	$ 0.20	$ 0.29	$ 0.24	$ 0.19	$ 0.21	$ 0.20	$ 0.34	$ 0.24
EPS - Diluted
Attributable to TECO Energy	$ 0.20	$ 0.29	$ 0.24	$ 0.19	$ 0.21	$ 0.20	$ 0.34	$ 0.23