Commitments And Contingencies (Environmental Remediation Liability Composed) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Topock natural gas compressor station	$ 294	[1]	$ 264	[1]
Hinkley natural gas compressor station	163	[1]	190	[1]
Former manufactured gas plant sites owned by the Utility or third parties	262		184
Utility-owned generation facilities (other than for fossil fuel-fired), other facilities, and third-party disposal sites	156		160
Fossil fuel-fired generation facilities and sites	101		102
Total environmental remediation liability	$ 976		$ 900

[1] See "Natural Gas Compressor Station Sites" below.