CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	Common stock	Additional Paid In Capital	Retained Earnings
Beginning Balance at Dec. 31, 2017	$ 876	$ 93	$ 449	$ 334
Balance (in shares) at Dec. 31, 2017		933,000
Increase (Decrease) in Stockholder's Equity
Net income	98			98
Dividends, Common Stock, Cash	(93)			(93)
Contribution of capital by parent	61		61
Ending Balance at Dec. 31, 2018	942	$ 93	510	339
Balance (in shares) at Dec. 31, 2018		933,000
Increase (Decrease) in Stockholder's Equity
Net income	79			79
Dividends, Common Stock, Cash	(81)			(81)
Contribution of capital by parent	27		27
Ending Balance at Dec. 31, 2019	$ 967	$ 93	537	337
Balance (in shares) at Dec. 31, 2019	933,000	933,000
Increase (Decrease) in Stockholder's Equity
Net income	$ 107			107
Dividends, Common Stock, Cash	(74)			(74)
Contribution of capital by parent	68		68
Ending Balance at Dec. 31, 2020	$ 1,068	$ 93	$ 605	$ 370
Balance (in shares) at Dec. 31, 2020	933,000	933,000