Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended	0 Months Ended
	Feb. 08, 2011 InsuranceCarrier Lawsuit	Mar. 31, 2015 Claims	Dec. 19, 2013	Mar. 31, 2011 Customer
Long Term Commitments [Line Items]
Gas supply disruption of high utility customers				32,000
Number of class dismissed		2
Period of appeal expires		30 days
Right to appeal expiration date		October 2014
Number of lawsuits for insurance carriers	2
Number of insurance carriers	18
Expected period for annulment proceedings		2 years
TECO Guatemala Holdings, LLC v. The Republic of Guatemala [Member]
Long Term Commitments [Line Items]
Litigation settlement amount			$ 7.5
Damages awarded			21.1
TECO Guatemala Holdings, LLC v. The Republic of Guatemala [Member] | U.S. prime rate plus [Member]
Long Term Commitments [Line Items]
Litigation settlement interest			2.00%
Gas Shortages [Member]
Long Term Commitments [Line Items]
Gas supply disruption of high utility customers	28,700
PGS [Member]
Long Term Commitments [Line Items]
Ultimate financial liability to superfund sites and former MGP sites		33.3
PGS [Member] | Tampa Electric Company [Member]
Long Term Commitments [Line Items]
Ultimate financial liability to superfund sites and former MGP sites		33.3