Regulatory Matters (Details 4) (GSWC, Costs deferred for future recovery on Aerojet case, USD $) In Millions, unless otherwise specified	1 Months Ended		12 Months Ended
	Oct. 31, 2005	Jul. 31, 2005	Dec. 31, 2012
Regulatory matters:
Regulatory asset authorized under settlement		$ 21.3
Recovery periods	20 years	20 years
Reimbursement to recover costs			17.5
Litigation costs contingently reimbursable under terms of settlement			$ 17.5
Maximum
Regulatory matters:
Recovery periods			20 years