Assumed Life Reinsurance Programs Involving Minimum Benefit Guarantees Under Annuity Contracts (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 Guaranteed Minimum Death Benefit [Member]	Dec. 31, 2013 Guaranteed Minimum Death Benefit [Member]	Jun. 30, 2014 Guaranteed Minimum Income Benefit [Member]	Dec. 31, 2013 Guaranteed Minimum Income Benefit [Member]	Jun. 30, 2013 Guaranteed Minimum Income Benefit [Member]	Mar. 31, 2013 Guaranteed Minimum Income Benefit [Member]	Dec. 31, 2012 Guaranteed Minimum Income Benefit [Member]	Jun. 30, 2014 Guaranteed Minimum Deaths Benefits And Guaranteed Living Benefits [Member]	Dec. 31, 2013 Guaranteed Minimum Deaths Benefits And Guaranteed Living Benefits [Member]	Jun. 30, 2014 Guaranteed Living Benefits [Member]	Dec. 31, 2013 Guaranteed Living Benefits [Member]
Guaranteed Minimum Benefits [Line Items]
Reported liabilities		$ 107	$ 100	$ 486	$ 427	$ 880	$ 1,000	$ 1,400
Fair value derivative adjustment in liability				241	193
Net amount at risk		601	586								173	136
Mortality percentage according to Annuity 2000 mortality table											100.00%
Discounting assumption used in the calculation of the benefit reserve averaging - lower range		1.50%							3.00%		3.50%
Discounting assumption used in the calculation of the benefit reserve averaging - upper range		2.50%							4.00%		4.50%
Total claim amount payable, if all of the Company's cedants' policyholders covered were to die immediately		676							64
GMBD net amount of risk									69	73
GLB net amount of risk									$ 142	$ 141
Average attained age of all policyholders under all benefits reinsured, years	69 years