Fair Value Measurements - Separate Account Assets (Details) (USD $) In Millions, unless otherwise specified					3 Months Ended
	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2014 Separate Account Assets [Member]		Mar. 31, 2013 Separate Account Assets [Member]		Mar. 31, 2014 Pension Benefits [Member]	Dec. 31, 2013 Pension Benefits [Member]	Mar. 31, 2014 Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Fair Value Inputs Level 1 [Member]	Mar. 31, 2014 Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Fair Value Inputs Level 2 [Member]	Mar. 31, 2014 Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Fair Value Inputs Level 3 [Member]	Mar. 31, 2014 Fair Value Inputs Level 3 [Member] Pension Benefits [Member]	Dec. 31, 2013 Fair Value Inputs Level 3 [Member] Pension Benefits [Member]
Financial assets and financial liabilities carried at fair value [Line Items]
Guaranteed separate accounts	$ 548		$ 548								$ 276	$ 264	$ 272	$ 284	$ 0	$ 0
Non-guaranteed separate accounts	7,840	[1]	7,704	[2]					3,900	3,800	1,847	1,844	4,924	4,825	1,069	1,035	1,015	983
Total separate account assets	8,388		8,252								2,123	2,108	5,196	5,109	1,069	1,035
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at January 1,					1,035		1,005
Policyholder gains (losses)					32	[3]	7	[3]
Purchases, issuances, settlements:
Purchases					44		31
Sales					0		0
Settlements					(47)		(30)
Total purchases, sales, settlements					(3)		1
Transfers into/(out of) Level 3:
Transfers into Level 3					7		0
Transfers out of Level 3					(2)		(2)
Total transfers into/(out of) Level 3					5		(2)
Balance at March 31,					1,069		1,011
Policyholder Gains Losses Attributable To Instruments Still Held					$ 32		$ 7

[1] As of March 31, 2014, non-guaranteed separate accounts included $3.9 billion in assets supporting the Company's pension plans, including $1,015 million classified in Level 3.

[2] As of December 31, 2013, non-guaranteed separate accounts included $3.8 billion in assets supporting the Company's pension plans, including $983 million classified in Level 3.

[3] Included in this amount are gains of $32 million attributable to instruments still held at March 31, 2014 and gains of $7 million attributable to instruments still held at March 31, 2013.