XML 110 R84.htm IDEA: XBRL DOCUMENT v3.3.1.900
Employee Postretirement Benefits - Schedule of Benefit Payments (Detail)
$ in Millions
Dec. 31, 2015
USD ($)
Pension Benefits [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected Benefit Payments - 2016 $ 77.8
Expected Benefit Payments - 2017 49.5
Expected Benefit Payments - 2018 52.7
Expected Benefit Payments - 2019 59.2
Expected Benefit Payments - 2020 54.9
Expected Benefit Payments - 2021-2025 299.1
Pension Benefits [Member] | TECO Energy [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected Benefit Payments - 2016 77.8
Expected Benefit Payments - 2017 49.5
Expected Benefit Payments - 2018 52.7
Expected Benefit Payments - 2019 59.2
Expected Benefit Payments - 2020 54.9
Expected Benefit Payments - 2021-2025 299.1
Other Postretirement Benefits [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected Benefit Payments - 2016 11.5
Expected Benefit Payments - 2017 11.9
Expected Benefit Payments - 2018 12.5
Expected Benefit Payments - 2019 13.0
Expected Benefit Payments - 2020 13.3
Expected Benefit Payments - 2021-2025 68.6
Other Postretirement Benefits [Member] | TECO Energy [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected Benefit Payments - 2016 11.5
Expected Benefit Payments - 2017 11.9
Expected Benefit Payments - 2018 12.5
Expected Benefit Payments - 2019 13.0
Expected Benefit Payments - 2020 13.3
Expected Benefit Payments - 2021-2025 $ 68.6