Invested Assets - Fair Value and Amortized Cost of Fixed Maturities by Contractual Maturity (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-For-Sale Securities [Line Items]
Due in one year or less, Fair Value	$ 2,097
Due after one year through five years, Fair Value	14,234
Due after five years through ten years, Fair Value	12,617
Due after ten years, Fair Value	8,313
Subtotal fixed maturities, Fair Value	37,261
Total fixed maturities, Fair Value	38,589	37,091
Due in one year or less, Amortized Cost	2,073
Due after one year through five years, Amortized Cost	13,691
Due after five years through ten years, Amortized Cost	11,923
Due after ten years, Amortized Cost	7,862
Subtotal fixed maturities, Amortized Cost	35,549
Total fixed maturities, Amortized Cost	36,838	35,959
Residential Mortgage-backed Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	230
Taxable, Amortized Cost	210
Commercial Mortgage-backed Securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Taxable, Fair Value	1,098
Taxable, Amortized Cost	$ 1,079