Reinsurance - Life Insurance Contract Holders' Benefits Incurred on Ceded Business (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Assumed earned premiums	$ 3	$ 2
Net incurred loss and loss expenses	732	568
Life Insurance Segment
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct policyholders' benefits incurred	80	64
Ceded policyholders' benefits incurred	(24)	(20)
Net incurred loss and loss expenses	$ 56	$ 44