Non-Insurance Revenues from Contracts with Customers (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Deferred non-insurance warranty revenue	$ 3,852		$ 3,852		$ 3,779
Contract with customer, liability, revenue recognized	$ 278	$ 246	$ 564	$ 511