Discontinued Operations - Components of Discontinued Operations (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss) Income from discontinued operations	$ 0	$ (0.2)	$ 5.0	$ 0.2
Less: Provision for income taxes	0	0	1.9	0.1
(Loss) Income from discontinued operations, net	0	(0.2)	3.1	0.1
TECO Guatemala [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	0	0	0	0
(Loss) Income from operations	0	(0.2)	5.0	0.2
(Loss) Income from discontinued operations	0	(0.2)	5.0	0.2
Less: Provision for income taxes	0	0	1.9	0.1
(Loss) Income from discontinued operations, net	$ 0	$ (0.2)	$ 3.1	$ 0.1