Consolidated Statements of Shareholder's Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	[1]	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	[1]
Beginning Balance at Dec. 31, 2019	$ 2,587	$ 119		$ 0	$ 161	$ (1,087)	$ 3,513	$ 119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	130						130
Other comprehensive (loss) income	(68)					(68)
Ending Balance at Sep. 30, 2020	2,768			0	161	(1,155)	3,762
Beginning Balance at Jun. 30, 2020	2,732			0	161	(1,165)	3,736
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	26						26
Other comprehensive (loss) income	10					10
Ending Balance at Sep. 30, 2020	2,768			0	161	(1,155)	3,762
Beginning Balance at Dec. 31, 2020	2,895			0	161	(1,099)	3,833
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	365						365
Other comprehensive (loss) income	(44)					(44)
Ending Balance at Sep. 30, 2021	3,216			0	161	(1,143)	4,198
Beginning Balance at Jun. 30, 2021	3,164			0	161	(1,106)	4,109
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	89						89
Other comprehensive (loss) income	(37)					(37)
Ending Balance at Sep. 30, 2021	$ 3,216			$ 0	$ 161	$ (1,143)	$ 4,198

[1] Represents $140 million, net of tax of $21 million, related to the impact as of January 1, 2020, of adopting the Current Expected Credit Loss (CECL) Methodology for the recognition of credit losses on certain financial instruments.