Insurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statutory Accounting Practices [Line Items]
Cash and cash equivalents	$ 22	$ 9
Marketable securities	703	697
Total cash, cash equivalents, and marketable securities	725	706
Assets Held by Insurance Regulators	12	12
Prepaid reinsurance premiums and other reinsurance recoverables	708	687
Related party transaction, prepaid reinsurance premiums and other reinsurance recoverables	97	97
Earned insurance premiums	213	207	$ 176
Insurance loss and loss adjustment expenses	88	84	71
Unearned insurance premiums and fees	822	806
Related Party Transactions Unearned Premiums and Fees	711	696
Premiums Written and Earned [Abstract]
Direct premiums written	366	406	392
Assumed premiums written	0	0	0
Ceded premiums written	(229)	(223)	(225)
Net premiums written	137	183	167
Direct premiums earned	350	377	346
Assumed premiums earned	0	0	0
Ceded premiums earned	(207)	(195)	(179)
Premiums Earned, Net	143	182	167
Insurance Expenses [Abstract]
Insurance losses	110	128	101
Loss adjustment expenses	5	7	5
Reinsurance Income and Other Expenses, Net	(33)	(32)	(29)
Insurance expenses	82	103	77
Liability for reported insurance claims and estimate of unreported claims	12
Ceded insurance expenses	$ 130	$ 127	$ 114