PG&E Corporation is a holding company that conducts its business through Pacific Gas and Electric Company (Utility). The Utility's revenues are generated mainly through the sale and delivery of electricity and natural gas to customers. The Utility served approximately 5.2 million electricity distribution customers and approximately 4.4 million natural gas distribution customers at December 31, 2012. The Utility's rates for electricity and natural gas utility services are based on its costs of providing service (cost-of-service ratemaking). The Utility is regulated primarily by the California Public Utilities Commission (CPUC) and the Federal Energy Regulatory Commission (FERC). In addition, the Nuclear Regulatory Commission (NRC) oversees the licensing, construction, operation, and decommissioning of the Utility's nuclear generation facilities. During the year ended December 31, 2012, the Company delivered 76,205 gigawatts per hour of Actual Electricity.