Reserves in Addition to Account Balance, Based on Expected No-Lapse Guarantee Benefits and Expected Policy Assessments (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	$ 2,345	$ 2,295
Ordinary/Traditional Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	778	752
Universal Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	501	483
Deferred Annuities
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	858	850
Structured Settlements
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	192	193
Other
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	$ 16	$ 17