Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Stockholders’ equity-
Common stock, par value (in dollars per share)	$ 0.1	$ 0.1
Common stock, authorized (in shares)	700,000,000	700,000,000
Common stock, outstanding (in shares)	540,652,222	511,915,450
Preferred stock, par value (in dollars per share)	$ 100	$ 100
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred shares, outstanding (in shares)	0
Customer
Receivables-
Allowance for uncollectible accounts (in dollars)	$ 46	$ 50
Other
Receivables-
Allowance for uncollectible accounts (in dollars)	$ 21	$ 2
Series A Convertible Preferred Stock
Stockholders’ equity-
Common stock, outstanding (in shares)	0	700,000
Preferred stock, authorized (in shares)	1,616,000	1,616,000
Preferred shares, outstanding (in shares)	0	704,589
Affiliated companies
Receivables-
Allowance for uncollectible accounts (in dollars)	$ 1,063	$ 920