Consolidated Balance Sheets - Southern (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Other intangible assets, amortization	$ 307,000,000	$ 328,000,000
Common Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized (in shares)	1,500,000,000	1,500,000,000
Common stock, shares issued (in shares)	1,100,000,000	1,100,000,000
Treasury shares (in shares)	1,000,000.0	1,000,000.0
Redeemable Preferred Stock
Cumulative preferred stock
Annual dividend requirement	$ 15,000,000	$ 15,000,000
Redeemable Preferred Stock, $100 par or stated value
Cumulative preferred stock
Par value (in dollars per share)	$ 100	$ 100
Shares authorized (in shares)	10,000,000	10,000,000
Shares outstanding (in shares)	500,000	500,000
Redeemable Preferred Stock, $100 par or stated value | Minimum
Cumulative preferred stock
Dividend rate	4.20%	4.20%
Redeemable Preferred Stock, $100 par or stated value | Maximum
Cumulative preferred stock
Dividend rate	4.92%	4.92%
Redeemable Preferred Stock, $1 par value
Cumulative preferred stock
Par value (in dollars per share)	$ 1	$ 1
Dividend rate	5.00%	5.00%
Shares authorized (in shares)	28,000,000	28,000,000
Shares outstanding (in shares)	10,000,000	10,000,000