Fair Value Measurements - Financial Assets and Financial Liabilities Carried at Fair Value (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2014		Dec. 31, 2013
Financial assets at fair value:
Fixed maturities	$ 18,321		$ 16,486
Equity securities	131		141
Short-term investments	232		631
Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	18,321	[1]	16,486	[2]
Equity securities	131		141
Subtotal	18,452		16,627
Short-term investments	232		631
Total financial assets at fair value, excluding separate accounts	19,549		18,012
Financial liabilities at fair value:
Total financial liabilities at fair value	856		757
Run-off Settlement Annuity Business [Member] | Fair Value, Measurements, Recurring [Member]
Financial liabilities at fair value:
Net appreciation required to adjust future policy benefits for run-off settlement annuity business included in fixed maturities	690		458
Other derivatives [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	2	[3]	3	[4]
Financial liabilities at fair value:
Derivative liabilities	17	[3]	16	[4]
Other derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	2		3
Financial liabilities at fair value:
Derivative liabilities	17		15
Other derivatives [Member] | Non designated [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	0		0
Financial liabilities at fair value:
Derivative liabilities	0		1
Guaranteed Minimum Income Benefit [Member]
Financial liabilities at fair value:
Percentage of GMIB exposure covered by retrocessional coverage	100.00%		100.00%
Number of external reinsurers	3		3
Guaranteed Minimum Income Benefit [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	863	[5]	751	[6]
Financial liabilities at fair value:
Derivative liabilities	839		741
Federal government and agency [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	1,252		880
State and local government [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	2,023		2,144
Foreign government [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	1,706		1,444
Corporate [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	12,397		10,981
Federal agency mortgage-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	69		76
Other mortgage-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	78		77
Other asset-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	796		884
Fair Value Inputs Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	583	[1]	297	[2]
Equity securities	1		8
Subtotal	584		305
Short-term investments	0		0
Total financial assets at fair value, excluding separate accounts	584		305
Financial liabilities at fair value:
Total financial liabilities at fair value	0		0
Fair Value Inputs Level 1 [Member] | Other derivatives [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	0	[3]	0	[4]
Financial liabilities at fair value:
Derivative liabilities	0	[3]	0	[4]
Fair Value Inputs Level 1 [Member] | Guaranteed Minimum Income Benefit [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	0	[5]	0	[6]
Financial liabilities at fair value:
Derivative liabilities	0		0
Fair Value Inputs Level 1 [Member] | Federal government and agency [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	583		297
Fair Value Inputs Level 1 [Member] | State and local government [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 1 [Member] | Foreign government [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 1 [Member] | Corporate [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 1 [Member] | Federal agency mortgage-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 1 [Member] | Other mortgage-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 1 [Member] | Other asset-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	16,664	[1]	15,058	[2]
Equity securities	82		74
Subtotal	16,746		15,132
Short-term investments	232		631
Total financial assets at fair value, excluding separate accounts	16,980		15,766
Financial liabilities at fair value:
Total financial liabilities at fair value	17		16
Fair Value Inputs Level 2 [Member] | Other derivatives [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	2	[3]	3	[4]
Financial liabilities at fair value:
Derivative liabilities	17	[3]	16	[4]
Fair Value Inputs Level 2 [Member] | Guaranteed Minimum Income Benefit [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	0	[5]	0	[6]
Financial liabilities at fair value:
Derivative liabilities	0		0
Fair Value Inputs Level 2 [Member] | Federal government and agency [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	669		583
Fair Value Inputs Level 2 [Member] | State and local government [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	2,023		2,144
Fair Value Inputs Level 2 [Member] | Foreign government [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	1,677		1,421
Fair Value Inputs Level 2 [Member] | Corporate [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	11,897		10,476
Fair Value Inputs Level 2 [Member] | Federal agency mortgage-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	69		76
Fair Value Inputs Level 2 [Member] | Other mortgage-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	77		76
Fair Value Inputs Level 2 [Member] | Other asset-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	252		282
Fair Value Inputs Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	1,074	[1]	1,131	[2]
Equity securities	48		59
Subtotal	1,122		1,190
Short-term investments	0		0
Total financial assets at fair value, excluding separate accounts	1,985		1,941
Financial liabilities at fair value:
Total financial liabilities at fair value	839		741
Fair Value Inputs Level 3 [Member] | Run-off Settlement Annuity Business [Member] | Fair Value, Measurements, Recurring [Member]
Financial liabilities at fair value:
Net appreciation required to adjust future policy benefits for run-off settlement annuity business included in fixed maturities	78		60
Fair Value Inputs Level 3 [Member] | Other derivatives [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	0	[3]	0	[4]
Financial liabilities at fair value:
Derivative liabilities	0	[3]	0	[4]
Fair Value Inputs Level 3 [Member] | Guaranteed Minimum Income Benefit [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Derivative assets	863	[5]	751	[6]
Financial liabilities at fair value:
Derivative liabilities	839		741
Fair Value Inputs Level 3 [Member] | Federal government and agency [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 3 [Member] | State and local government [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 3 [Member] | Foreign government [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	29		23
Fair Value Inputs Level 3 [Member] | Corporate [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	500		505
Fair Value Inputs Level 3 [Member] | Federal agency mortgage-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	0		0
Fair Value Inputs Level 3 [Member] | Other mortgage-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	1		1
Fair Value Inputs Level 3 [Member] | Other asset-backed [Member] | Fair Value, Measurements, Recurring [Member]
Financial assets at fair value:
Fixed maturities	$ 544		$ 602

[1] Fixed maturities included $690 million of net appreciation required to adjust future policy benefits for the run-off settlement annuity business including $78 million of appreciation for securities classified in Level 3.

[2] Fixed maturities included $458 million of net appreciation required to adjust future policy benefits for the run-off settlement annuity business including $60 million of appreciation for securities classified in Level 3.

[3] Other derivative assets and other derivative liabilities reflected foreign currency and interest rate swaps qualifying as cash flow hedges. See Note 9 for additional information.

[4] Other derivative assets reflected interest rate and foreign currency swaps qualifying as cash flow hedges. Other derivative liabilities included $15 million of interest rate and foreign currency swaps qualifying as cash flow hedges and $1 million of interest rate and foreign currency swaps not designated as accounting hedges. See Note 9 for additional information.

[5] The GMIB assets represent retrocessional contracts in place from three external reinsurers that cover the exposures on these contracts. See Note 5 for additional information.

[6] The GMIB assets represented retrocessional contracts in place from three external reinsurers that cover the exposures on these contracts. See Note 5 for additional information.