Fair Values of Assets and Liabilities Fair Values of Assets and Liabilities (Level 3 rollforwards-Assets) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013		Jun. 30, 2014	Jun. 30, 2013
Corporate Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 1,391	$ 1,653		$ 1,516	$ 1,654
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(1)			(1)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	10	(35)		15	(35)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	33	20		57	74
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				(11)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(58)	(79)		(201)	(134)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	1,376	1,558		1,376	1,558
Changes in unrealized gains (losses) relating to assets and liabilities held at the end of the period included in:
Net investment income					(1)
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	11	8		58	23
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		42		11	42
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(1)			(1)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				(58)	(15)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	10	50		10	50
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	55	168		30	170
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(4)			(6)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				39
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(40)			(54)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	15	164		15	164
Asset backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	149	160		218	156
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	1	3		1	7
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(1)			(1)	(1)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(9)		(69)	(9)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	149	154		149	154
Changes in unrealized gains (losses) relating to assets and liabilities held at the end of the period included in:
Net investment income					1
Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	1,606	1,989		1,822	2,003
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(1)	[1]		0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	11	(36)		16	(34)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	33	62		107	116
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				(11)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(60)	(79)		(203)	(135)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(40)	(9)		(181)	(24)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	1,550	1,926		1,550	1,926
Changes in unrealized gains (losses) relating to assets and liabilities held at the end of the period included in:
Net investment income		0			0
Common Stock [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	1			1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	1			1
Other Contract [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	1			1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	1			1
Changes in unrealized gains (losses) relating to assets and liabilities held at the end of the period included in:
Benefits, claims, losses and settlement expenses	$ 0			$ 0

[1] Included in net investment income in the Consolidated Statements of Income.