Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Property and casualty claim and claim adjustment expense reserves	$ 178	$ 265
Unearned premium reserves	230	187
Receivables	30	37
Employee benefits	419	432
Life settlement contracts	48	46
Deferred retroactive reinsurance benefit	84	61
Net operating loss carryforwards	245	321
Tax credit carryforwards	131	93
Basis differential in investment in subsidiary	19	21
Other	282	209
Total deferred tax assets	1,666	1,672
Valuation allowance	(147)	(48)
Net deferred tax assets	1,519	1,624
Deferred tax liabilities:
Deferred acquisition costs	(117)	(226)
Net unrealized gains	(166)	(469)
Property, plant and equipment	(998)	(1,132)
Basis differential in investment in subsidiary	(428)	(472)
Other liabilities	(173)	(204)
Deferred tax liabilities	(1,882)	(2,503)
Net deferred tax liability	$ (363)	$ (879)