v3.3.1.900
Power purchase agreements, etc. - amortization (Details)
$ in Millions
12 Months Ended
Dec. 31, 2015
USD ($)
Power Purchase Agreements  
Estimated future amortization expense  
2016 $ 34.9
2017 32.9
2018 26.1
2019 25.4
2020 $ 22.4
Weighted average remaining amortization period related to our intangible assets  
Weighted average remaining amortization period 7 years 8 months 12 days
Fuel Supply Agreements  
Estimated future amortization expense  
2016 $ (1.2)
2017 (1.2)
2018 (1.2)
2019 (1.2)
2020 $ (1.2)
Weighted average remaining amortization period related to our intangible assets  
Weighted average remaining amortization period 7 years 7 months 6 days