Reinsurance - Earned Life Insurance Premiums on Ceded Business (Detail) - Life Insurance Segment - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct earned premiums	$ 74	$ 67	$ 220	$ 200
Ceded earned premiums	(16)	(16)	(45)	(44)
Earned premiums	$ 58	$ 51	$ 175	$ 156