CONTINGENCIES AND COMMITMENTS (Regulatory Proceedings) (Details) - USD ($)					6 Months Ended	9 Months Ended
	Jan. 01, 2019	Sep. 21, 2018	May 17, 2018	Apr. 26, 2018	Jun. 30, 2018	Sep. 30, 2018
Loss Contingencies [Line Items]
Maximum statutory penalty						$ 50,000
Administrative limit						8,000,000
Forecast
Loss Contingencies [Line Items]
Maximum statutory penalty	$ 100,000
Minimum
Loss Contingencies [Line Items]
Fines incurred in prior periods						50,000
Maximum
Loss Contingencies [Line Items]
Fines incurred in prior periods						$ 16,800,000
Pacific Gas & Electric Co | Electric
Loss Contingencies [Line Items]
Requested revenue rate		98.85%
Ex Parte Communications
Loss Contingencies [Line Items]
Proposed penalty				$ 97,500,000
Payment to State General Fund			$ 12,000,000	12,000,000
Gas transmission and storage revenue reduction				63,500,000
2018 GTandS revenue requirement reduction				31,750,000
2019 GTandS revenue requirement reduction				31,750,000
Revenue requirement reduction in Next GRC cycle				10,000,000
Payment to city of San Bruno			6,000,000	6,000,000
Payment to city of San Carlos			$ 6,000,000	$ 6,000,000
Disallowance of Plant Costs
Loss Contingencies [Line Items]
Accrual for GTandS revenue requirement reduction					$ 24,000,000