Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Movement Analysis of Deferred Policy Acquisition Costs
Deferred policy acquisition costs asset, beginning of period	$ 786	$ 728	$ 738	$ 670
Capitalized deferred policy acquisition costs	271	244	836	755
Amortized deferred policy acquisition costs	(270)	(231)	(767)	(701)
Shadow deferred policy acquisition costs	(4)	2	(24)	19
Deferred policy acquisition costs asset, end of period	783	743	783	743
Consolidated Property and Casualty Insurance Entity
Movement Analysis of Deferred Policy Acquisition Costs
Deferred policy acquisition costs asset, beginning of period	526	472	464	438
Capitalized deferred policy acquisition costs	256	229	790	712
Amortized deferred policy acquisition costs	(257)	(225)	(729)	(674)
Deferred policy acquisition costs asset, end of period	525	476	525	476
Life Insurance Segment
Movement Analysis of Deferred Policy Acquisition Costs
Deferred policy acquisition costs asset, beginning of period	260	256	274	232
Capitalized deferred policy acquisition costs	15	15	46	43
Amortized deferred policy acquisition costs	(13)	(6)	(38)	(27)
Shadow deferred policy acquisition costs	(4)	2	(24)	19
Deferred policy acquisition costs asset, end of period	$ 258	$ 267	$ 258	$ 267