Assumed Life Reinsurance Programs Involving Minimum Benefit Guarantees Under Annuity Contracts (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014 Guaranteed Minimum Death Benefit [Member]	Dec. 31, 2013 Guaranteed Minimum Death Benefit [Member]	Mar. 31, 2014 Guaranteed Minimum Income Benefit [Member]	Dec. 31, 2013 Guaranteed Minimum Income Benefit [Member]	Mar. 31, 2013 Guaranteed Minimum Income Benefit [Member]	Dec. 31, 2012 Guaranteed Minimum Income Benefit [Member]	Mar. 31, 2014 Guaranteed Minimum Deaths Benefits And Guaranteed Living Benefits [Member]	Dec. 31, 2013 Guaranteed Minimum Deaths Benefits And Guaranteed Living Benefits [Member]	Mar. 31, 2014 Guaranteed Living Benefits [Member]	Dec. 31, 2013 Guaranteed Living Benefits [Member]
Guaranteed Minimum Benefits [Line Items]
Reported liabilities		$ 104	$ 100	$ 483	$ 427	$ 1,000	$ 1,400
Fair value derivative adjustment in liability				243	193
Net amount at risk		645	586							163	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		666						93
GMBD net amount of risk								73
GLB net amount of risk								$ 158	$ 141
Average attained age of all policyholders under all benefits reinsured, years	68 years