Benefit Plans (Reconciliation of Level 3 Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Corporate and other bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at December 31	$ 520	$ 447
Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at December 31	841	804
Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at December 31	605	493
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at December 31	969	896
Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at December 31	114	62
Total limited partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at December 31	1,083	958
Investment Contracts with Insurance Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at December 31		10
Total assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at December 31	2,656	2,425
Fair Value, Inputs, Level 3 [Member] | Corporate and other bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	11	10
Defined Benefit Plan, Actual Return on Plan Assets Still Held	(1)	1
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period
Defined Benefit Plan, Purchases, Sales, and Settlements	5
Defined Benefit Plan, Net transfers into (out of) Level 3
Fair value of plan assets at December 31	15	11
Fair Value, Inputs, Level 3 [Member] | Fixed Maturities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	11	10
Defined Benefit Plan, Actual Return on Plan Assets Still Held		1
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	(1)
Defined Benefit Plan, Purchases, Sales, and Settlements	5
Defined Benefit Plan, Net transfers into (out of) Level 3
Fair value of plan assets at December 31	15	11
Fair Value, Inputs, Level 3 [Member] | Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	5	5
Defined Benefit Plan, Actual Return on Plan Assets Still Held	3
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period
Defined Benefit Plan, Purchases, Sales, and Settlements
Defined Benefit Plan, Net transfers into (out of) Level 3
Fair value of plan assets at December 31	8	5
Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	359	330
Defined Benefit Plan, Actual Return on Plan Assets Still Held	56	41
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period		3
Defined Benefit Plan, Purchases, Sales, and Settlements	(77)	(15)
Defined Benefit Plan, Net transfers into (out of) Level 3	(16)
Fair value of plan assets at December 31	322	359
Fair Value, Inputs, Level 3 [Member] | Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	62	65
Defined Benefit Plan, Actual Return on Plan Assets Still Held		8
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period
Defined Benefit Plan, Purchases, Sales, and Settlements	52	(11)
Defined Benefit Plan, Net transfers into (out of) Level 3
Fair value of plan assets at December 31	114	62
Fair Value, Inputs, Level 3 [Member] | Total limited partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	421	395
Defined Benefit Plan, Actual Return on Plan Assets Still Held	56	49
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period		3
Defined Benefit Plan, Purchases, Sales, and Settlements	(25)	(26)
Defined Benefit Plan, Net transfers into (out of) Level 3	(16)
Fair value of plan assets at December 31	436	421
Fair Value, Inputs, Level 3 [Member] | Investment Contracts with Insurance Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	10	10
Defined Benefit Plan, Actual Return on Plan Assets Still Held
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period
Defined Benefit Plan, Purchases, Sales, and Settlements	(10)
Defined Benefit Plan, Net transfers into (out of) Level 3
Fair value of plan assets at December 31		10
Fair Value, Inputs, Level 3 [Member] | Total assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	447	420
Defined Benefit Plan, Actual Return on Plan Assets Still Held	58	50
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period		3
Defined Benefit Plan, Purchases, Sales, and Settlements	(30)	(26)
Defined Benefit Plan, Net transfers into (out of) Level 3	(16)
Fair value of plan assets at December 31	$ 459	$ 447