Reserves in Addition to Account Balance, Based on Expected No-Lapse Guarantee Benefits and Expected Policy Assessments (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	$ 2,514	$ 2,497
Ordinary/Traditional Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	891	875
Deferred Annuities
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	863	863
Universal Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	533	530
Structured Settlements
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	181	182
Other
Liability for Future Policy Benefit, by Product Segment [Line Items]
Life policy and investment contract reserves	$ 46	$ 47