Contracts Accounted for as Insurance - Gross Premium Receivable Net of Commissions on Assumed Business Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
Beginning of period	$ 576	$ 693
Premiums receivable from acquisitions (see Note 2)	270	0
Gross written premiums on new business, net of commissions on assumed business	110	41
Gross premiums received, net of commissions on assumed business	(92)	(49)
Adjustments:
Changes in the expected term	(1)	(22)
Accretion of discount, net of commissions on assumed business	4	0
Foreign exchange translation	9	(1)
End of period	876	662
Variable Interest Entity, Primary Beneficiary [Member]
Adjustments:
End of period	$ 11	$ 16