Insurance (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Liability for unpaid claims and claims adjustment expense
Balance at beginning of period	$ 117	$ 117
Less reinsurance recoverables	(3)	(3)	$ (4)	$ (4)
Net balance at beginning of period			113	113
Additions for losses and loss adjustment expenses incurred to:
Current year	221	154
Prior years	(10)	(13)
Total	211	141
Reductions for losses and loss adjustment expenses paid related to:
Current year	(107)	(85)
Prior years	(60)	(57)
Total	(167)	(142)
Net balance at end of period	157	112
Plus reinsurance recoverables	3	3	$ 4	$ 4
Balance at end of period	160	115
Net reserves	$ 10	$ 13