EARNINGS PER SHARE (Reconciliation of PG&E Corporation's Income Available for Common Shareholders and Weighted Average Shares of Common Stock Outstanding for Calculating Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Loss attributable to common shareholders	$ (1,318)	$ (7,656)	$ (6,851)
Weighted average common shares outstanding, basic (in shares)	1,257	528	517
Add incremental shares from assumed conversions:
Employee share-based compensation (in shares)	0	0	0
Equity Units (in shares)	0	0	0
Weighted average common share outstanding, diluted (in shares)	1,257	528	517
Total Loss per common share, diluted (in dollars per share)	$ (1.05)	$ (14.50)	$ (13.25)