Deferred Acquisition Costs - Deferred Policy Acquisition Costs and Asset Reconciliation (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	$ 660	$ 618	$ 637	$ 616
Capitalized deferred policy acquisition costs	249	230	488	452
Deferred Policy Acquisition Cost, Amortization Expense	(229)	(214)	(443)	(426)
Deferred Policy Acquisition Cost, Amortization Expense, Other	(2)	(10)	(4)	(18)
Deferred policy acquisition costs asset, end of period	678	624	678	624
Life Insurance Product Line [Member]
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	232	221	229	228
Capitalized deferred policy acquisition costs	12	12	25	24
Deferred Policy Acquisition Cost, Amortization Expense	(12)	(11)	(20)	(22)
Deferred Policy Acquisition Cost, Amortization Expense, Other	(2)	(10)	(4)	(18)
Deferred policy acquisition costs asset, end of period	230	212	230	212
Consolidated Property and Casualty Insurance Entity
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs asset, beginning of period	428	397	408	388
Capitalized deferred policy acquisition costs	237	218	463	428
Deferred Policy Acquisition Cost, Amortization Expense	(217)	(203)	(423)	(404)
Deferred policy acquisition costs asset, end of period	$ 448	$ 412	$ 448	$ 412