Fair Value Measurements (Financial Instruments Measured At Fair Value On Recurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	$ 49,254		$ 47,306
Equity securities	837		744
Short-term investments	1,763		2,228
Other investments	2,976		2,716
Securities lending collateral	1,632		1,791
Level 1
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	1,849		2,292
Equity securities	373		253
Short-term investments	953		1,503
Other investments	305		268
Securities lending collateral
Investment derivative instruments, assets	19		11
Other derivative instruments, assets			(6)
Separate account assets	1,145		872
Total assets measured at fair value	4,644		5,193
Investment derivative instruments, liability	6
Other derivative instruments, liability	60
GLB		[1]		[1]
Total liabilities measured at fair value	66
Level 1 | U.S. Treasury and agency
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	1,626		2,050
Level 1 | Foreign
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	223		222
Level 1 | Corporate securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value			20
Level 1 | Mortgage backed-securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value
Level 1 | States, municipalities, and political subdivisions
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value
Level 2
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	47,187		44,839
Equity securities	460		488
Short-term investments	803		725
Other investments	231		196
Securities lending collateral	1,632		1,791
Investment derivative instruments, assets
Other derivative instruments, assets	6		30
Separate account assets	81		71
Total assets measured at fair value	50,400		48,140
Investment derivative instruments, liability
Other derivative instruments, liability	2
GLB		[1]		[1]
Total liabilities measured at fair value	2
Level 2 | U.S. Treasury and agency
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	1,323		1,685
Level 2 | Foreign
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	14,324		13,431
Level 2 | Corporate securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	17,304		16,586
Level 2 | Mortgage backed-securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	10,886		10,460
Level 2 | States, municipalities, and political subdivisions
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	3,350		2,677
Level 3
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	218		175
Equity securities	4		3
Short-term investments	7
Other investments	2,440		2,252
Securities lending collateral
Investment derivative instruments, assets
Other derivative instruments, assets
Separate account assets
Total assets measured at fair value	2,669		2,430
Investment derivative instruments, liability
Other derivative instruments, liability
GLB	193	[1]	1,119	[1]
Total liabilities measured at fair value	193
Level 3 | U.S. Treasury and agency
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value
Level 3 | Foreign
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	44		60
Level 3 | Corporate securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	166		102
Level 3 | Mortgage backed-securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	8		13
Level 3 | States, municipalities, and political subdivisions
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value
Total
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	49,254		47,306
Equity securities	837		744
Short-term investments	1,763		2,228
Other investments	2,976		2,716
Securities lending collateral	1,632		1,791
Investment derivative instruments, assets	19		11
Other derivative instruments, assets	6		24
Separate account assets	1,226		943
Total assets measured at fair value	57,713		55,763
Investment derivative instruments, liability	6
Other derivative instruments, liability	62
GLB	193	[1]	1,119	[1]
Total liabilities measured at fair value	261
Total | U.S. Treasury and agency
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	2,949		3,735
Total | Foreign
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	14,591		13,713
Total | Corporate securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	17,470		16,708
Total | Mortgage backed-securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	10,894		10,473
Total | States, municipalities, and political subdivisions
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fixed maturities available for sale at fair value	$ 3,350		$ 2,677

[1] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB derivative liability classified as Future policy benefits in the consolidated balance sheets. Refer to Note 5 c) for additional information.