Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	$ 738	$ 670
Capitalized deferred policy acquisition costs	270	245
Deferred Policy Acquisition Costs, Amortization Expense	(246)	(234)
Deferred Policy Acquisition Cost, Amortization Expense, Other	(11)	10
Deferred policy acquisition costs asset, end of period	751	691
Consolidated Property and Casualty Insurance Entity
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	464	438
Capitalized deferred policy acquisition costs	254	232
Deferred Policy Acquisition Costs, Amortization Expense	(233)	(224)
Deferred policy acquisition costs asset, end of period	485	446
Life Insurance Segment
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	274	232
Capitalized deferred policy acquisition costs	16	13
Deferred Policy Acquisition Costs, Amortization Expense	(13)	(10)
Deferred Policy Acquisition Cost, Amortization Expense, Other	(11)	10
Deferred policy acquisition costs asset, end of period	$ 266	$ 245