Contracts Accounted for as Insurance - Gross Premium Receivable Net of Commissions on Assumed Business Roll Forward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
Beginning of period	$ 576	$ 693	$ 729
Premiums receivable from acquisitions (see Note 2)	270	18	2
Gross written premiums on new business, net of commissions	301	193	198
Gross premiums received, net of commissions	(301)	(258)	(206)
Adjustments:
Changes in the expected term	(8)	(38)	(19)
Accretion of discount, net of commissions on assumed business	12	9	18
Foreign exchange translation	64	(41)	(25)
Consolidation/deconsolidation of FG VIEs	0	0	(4)
Subtotal	914	576	693
Other	1	0	0
End of period	915	576	693
Variable Interest Entity, Primary Beneficiary [Member]
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
Beginning of period	11	17
Adjustments:
End of period	$ 10	$ 11	$ 17