Employee Benefit Plans (Changes in Fair Value of Level 3 Pension and Post Retirement Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Pension Plans, Defined Benefit [Member] | Debt Securities [Member] | Corporate Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	$ 12	$ 10
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	(1)	0
Actual Return Assets Sold During Period	0	0
Purchases, Sales, Issuances and Settlements	0	(1)
Transfers into\out of level 3, Net	1	3
Fair Value, end of period	12	12
Pension Plans, Defined Benefit [Member] | Debt Securities [Member] | Other Fixed Maturities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	62	(8)
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	0	0
Actual Return Assets Sold During Period	0	0
Purchases, Sales, Issuances and Settlements	(4)	70
Transfers into\out of level 3, Net	0	0
Fair Value, end of period	58	62
Pension Plans, Defined Benefit [Member] | Debt Securities [Member] | Pooled Separate Accounts Asset [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	20	0
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	2	0
Actual Return Assets Sold During Period	0	0
Purchases, Sales, Issuances and Settlements	10	20
Transfers into\out of level 3, Net	0	0
Fair Value, end of period	32	20
Pension Plans, Defined Benefit [Member] | Real Estate [Member] | Pooled Separate Accounts Asset [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	318	216
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	40	39
Actual Return Assets Sold During Period	(1)	16
Purchases, Sales, Issuances and Settlements	(35)	47
Transfers into\out of level 3, Net	0
Fair Value, end of period	322	318
Pension Plans, Defined Benefit [Member] | Real Estate [Member] | Partnership Interest [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	105	42
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	5	0
Actual Return Assets Sold During Period	0	0
Purchases, Sales, Issuances and Settlements	75	63
Transfers into\out of level 3, Net	0	0
Fair Value, end of period	185	105
Pension Plans, Defined Benefit [Member] | Other Investment [Member] | Partnership Interest [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	552	219
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	32	22
Actual Return Assets Sold During Period	0	11
Purchases, Sales, Issuances and Settlements	14	300
Transfers into\out of level 3, Net	0	0
Fair Value, end of period	598	552
Pension Plans, Defined Benefit [Member] | Other Investment [Member] | Structured Finance [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period		658
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held		0
Actual Return Assets Sold During Period		44
Purchases, Sales, Issuances and Settlements		(702)
Transfers into\out of level 3, Net		0
Fair Value, end of period		0
Pension Plans, Defined Benefit [Member] | Other Investment [Member] | Hedge Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	678	570
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	57	(20)
Actual Return Assets Sold During Period	0	2
Purchases, Sales, Issuances and Settlements	(28)	126
Transfers into\out of level 3, Net	0	0
Fair Value, end of period	707	678
Other Postretirement Benefit Plans, Defined Benefit [Member] | Debt Securities [Member] | Corporate Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	2	2
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	0	0
Actual Return Assets Sold During Period	0	0
Purchases, Sales, Issuances and Settlements	0	0
Transfers into\out of level 3, Net	0	0
Fair Value, end of period	2	2
Other Postretirement Benefit Plans, Defined Benefit [Member] | Debt Securities [Member] | Other Fixed Maturities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, beginning of period	2	4
Defined Benefit Plan, Actual Return on Plan Assets [Abstract]
Actual Return On Assets Still Held	0	0
Actual Return Assets Sold During Period	0	0
Purchases, Sales, Issuances and Settlements	(6)	(2)
Transfers into\out of level 3, Net	0	0
Fair Value, end of period	$ (4)	$ 2