Reinsurance Level 4 Reinsurance Revenues (Details) - Life Annuity Accident and Health Insurance Product Line [Member] - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended	5 Months Ended	6 Months Ended
	Jun. 30, 2018	May 31, 2018	Jun. 30, 2017	May 31, 2018	Jun. 30, 2017
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Fee Income Earned Premium and Other Life	$ 201	$ 419	$ 594	$ 1,059	$ 1,235
Assumed Premiums Earned	10	19	28	48	59
Ceded Premiums Earned	(133)	(273)	(363)	(684)	(778)
Net Fee Income Earned Premium and Other Life	$ 78	$ 165	$ 259	$ 423	$ 516