Benefit Plans (Components of net periodic cost (benefit)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Insurance claims and policyholders’ benefits	$ 1,339	$ 1,293
Other operating expenses	303	276
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost on projected benefit obligation	23	26
Expected return on plan assets	(40)	(39)
Amortization of net actuarial loss	9	9
Settlement loss	4	2
Total non-service cost	(4)	(2)
Total net periodic pension cost (benefit)	(4)	(2)
Insurance claims and policyholders’ benefits	1	1
Other operating expenses	$ 3	$ 1