Consolidated Statements of Changes in Equity (Unaudited) - SPPC - USD ($) $ in Millions	Total	SPPC	SPPC Common Stock	SPPC Additional Paid-in Capital	SPPC Retained Earnings	SPPC Accumulated Other Comprehensive (Loss) Income, Net
Balance (shares) at Dec. 31, 2019			1,000
Balance at Dec. 31, 2019		$ 1,320	$ 0	$ 1,111	$ 210	$ (1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 4,628	90			90
Dividends declared		(20)			(20)
Balance (shares) at Sep. 30, 2020			1,000
Balance at Sep. 30, 2020		1,390	$ 0	1,111	280	(1)
Balance (shares) at Jun. 30, 2020			1,000
Balance at Jun. 30, 2020		1,338	$ 0	1,111	228	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 2,842	52			52
Balance (shares) at Sep. 30, 2020			1,000
Balance at Sep. 30, 2020		$ 1,390	$ 0	1,111	280	(1)
Balance (shares) at Dec. 31, 2020	76,000,000	1,000	1,000
Balance at Dec. 31, 2020	$ 43,010	$ 1,411	$ 0	1,111	301	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 4,207	$ 107			107
Balance (shares) at Sep. 30, 2021	76,000,000	1,000	1,000
Balance at Sep. 30, 2021	$ 45,692	$ 1,518	$ 0	1,111	408	(1)
Balance (shares) at Jun. 30, 2021			1,000
Balance at Jun. 30, 2021		1,456		1,111	346	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 1,922	$ 62			62
Balance (shares) at Sep. 30, 2021	76,000,000	1,000	1,000
Balance at Sep. 30, 2021	$ 45,692	$ 1,518	$ 0	$ 1,111	$ 408	$ (1)