Consolidated Statements of Shareholder's Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]		Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	[1]
Beginning Balance at Dec. 31, 2018	$ 2,196			$ 0	$ 161	$ (1,060)	$ 3,095
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	215						215
Other comprehensive income (loss)	(15)					(15)	0
Ending Balance at Jun. 30, 2019	2,396			0	161	(1,075)	3,310
Beginning Balance at Mar. 31, 2019	2,306			0	161	(1,053)	3,198
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	112						112
Other comprehensive income (loss)	(22)					(22)	0
Ending Balance at Jun. 30, 2019	2,396			0	161	(1,075)	3,310
Beginning Balance at Dec. 31, 2019	$ 2,587	$ 119	[1]	0	161	(1,087)	3,513	$ 119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Ending Balance at Jan. 01, 2020		119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of new accounting guidance, tax		21
Beginning Balance at Dec. 31, 2019	$ 2,587	119	[1]	0	161	(1,087)	3,513	$ 119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	104						104
Other comprehensive income (loss)	(78)					(78)	0
Ending Balance at Jun. 30, 2020	2,732			0	161	(1,165)	3,736
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Impact of new accounting guidance, net of tax		$ 140
Beginning Balance at Mar. 31, 2020	2,591			0	161	(1,224)	3,654
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	82						82
Other comprehensive income (loss)	59					59	0
Ending Balance at Jun. 30, 2020	$ 2,732			$ 0	$ 161	$ (1,165)	$ 3,736

[1] Represents $140 million, net of tax of $21 million, related to the impact as of January 1, 2020, of adopting the new accounting guidance for the recognition of credit losses on certain financial instruments.