Operating Revenues Our operating revenues are derived from sales to our members and non-members and are recorded when power, including renewable energy credits, is delivered . We sell energy to our Class A members pursuant to long-term wholesale power contracts that we maintain with each of our member distribution cooperatives. These wholesale power contracts obligate each member distribution cooperative to pay us for power furnished in accordance with our rates. For t he years ended December 31, 2014, 2013, and 2012 , revenue from sales to our member distribution cooperatives , including the sale of renewable energy credits, was $ 908.0 million, $ 810.1 million, and $ 826.8 million, respectively. For the years ended December 31, 2014, 2013, and 2012, the sale of renewable energy credits included in revenue from sales to our member distribution cooperatives was $1.3 million and $1.4 million in 2014 and 2013, respectively , and was immaterial in 2012 . See Note 5 Wholesale Power Contracts. We sell excess purchased and generated energy, if any, to TEC, our Class B member, or to third parties under FERC market-based rate authority. Sales to TEC consist of sales of excess energy that we do not need to meet the actual needs of our member distribution cooperatives. TEC s sales to third parties are reflected as non-m ember revenues; however, in 2014, 2013, and 2012 , TEC had no sales to third parties. Excess purchased and generated energy that is not sold to TEC is sold to PJM under its rates for providing energy imbalance service, or to third parties. For t he years ended December 31, 2014, 2013, and 2012 , energy sales to non-members , including the sale of renewable energy credits, were $ 43.5 million, $ 31.9 million, and $ 15.9 million, respectively. For the years ended December 31, 2014, 2013, and 2012, the sale of renewable energy credits included in energy sales to non-members was $5.9 million, $6.1 million, and $0.5 million, respectively.