Benefit Plans (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Actual percentage of plan assets	100.00%	100.00%
Total plan assets at fair value	$ 5,802	$ 5,830
Total plan assets at fair value, allocation (as a percent)	100.00%	100.00%
Securities lending obligation	(290)	(463)
Other net plan assets	90	31
Total reported plan assets	5,602	5,398	4,675
Pension plan assets
Fair value of plan assets, beginning of year	5,398	4,675
Fair value of plan assets, end of year	5,602	5,398	4,675
Expected weighted average long-term rate of return on plan assets (as a percent)	7.75%	8.50%	8.50%
Expected weighted average long-term rate of return on plan assets for the next fiscal year (as a percent)	7.36%
Percentage of total plan assets for employee-agents	14.00%
Percentage of total plan assets for primary employee	79.00%
Arithmetic average of the annual actual return on plan assets for the last 10 years (as a percent)	8.00%
Arithmetic average of the annual actual return on plan assets for the last 5 years (as a percent)	11.30%
Cash flows
Defined benefit pension plans, estimated employer contributions in next fiscal year	38
Employer contribution	561	439
Participant contributions	1	1
Estimated future benefit payments
2014	355
2015	367
2016	390
2017	420
2018	438
2019-2023	2,481
Total benefit payments	4,451
Pension benefits | Minimum
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Notional amount of derivatives, maximum percentage of plan assets	105.00%
Pension benefits | Maximum
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Notional amount of derivatives, maximum percentage of plan assets	115.00%
Pension benefits | Quoted prices in active markets for identical assets (Level 1)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	847	1,021
Total plan assets at fair value, allocation (as a percent)	14.60%	17.50%
Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	4,265	3,863
Total plan assets at fair value, allocation (as a percent)	73.50%	66.30%
Pension benefits | Significant unobservable inputs (Level 3)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	690	946
Total plan assets at fair value, allocation (as a percent)	11.90%	16.20%
Total reported plan assets	690	946	938
Pension plan assets
Fair value of plan assets, beginning of year	946	938	992
Actual return on plan assets: Relating to assets sold during the period	15	30	36
Actual return on plan assets: Relating to assets still held at the reporting date	28	3	10
Purchases, sales and settlements, net	(299)	(25)	(82)
Net transfers in and/or (out) of Level 3			(18)
Fair value of plan assets, end of year	690	946	938
Postretirement benefits
Cash flows
Employer contribution	39	39
Participant contributions	18	20
Estimated future benefit payments
2014	35
2015	36
2016	29
2017	30
2018	32
2019-2023	188
Total benefit payments	350
Equity securities | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Target asset allocation, minimum range (as a percent)	40.00%
Target asset allocation, maximum range (as a percent)	50.00%
Actual percentage of plan assets	49.00%	50.00%
U.S. equity securities | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	2,202	2,123
U.S. equity securities | Pension benefits | Quoted prices in active markets for identical assets (Level 1)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value		13
U.S. equity securities | Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	2,124	2,042
U.S. equity securities | Pension benefits | Significant unobservable inputs (Level 3)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	78	68
Total reported plan assets	78	68	64
Pension plan assets
Fair value of plan assets, beginning of year	68	64	6
Actual return on plan assets: Relating to assets still held at the reporting date	10	7	(2)
Purchases, sales and settlements, net		(3)	60
Fair value of plan assets, end of year	78	68	64
International equity securities | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	501	580
International equity securities | Pension benefits | Quoted prices in active markets for identical assets (Level 1)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	160	136
International equity securities | Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	182	198
International equity securities | Pension benefits | Significant unobservable inputs (Level 3)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	159	246
Total reported plan assets	159	246	245
Pension plan assets
Fair value of plan assets, beginning of year	246	245	253
Actual return on plan assets: Relating to assets sold during the period	3
Actual return on plan assets: Relating to assets still held at the reporting date	8	1	(5)
Purchases, sales and settlements, net	(98)		(3)
Fair value of plan assets, end of year	159	246	245
Fixed income securities | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Target asset allocation, minimum range (as a percent)	43.00%
Target asset allocation, maximum range (as a percent)	52.00%
Actual percentage of plan assets	41.00%	38.00%
Cash collateral from target asset allocation, investment allocation (as a percent)	7.00%
U.S. government and agencies | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	660	877
U.S. government and agencies | Pension benefits | Quoted prices in active markets for identical assets (Level 1)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	608	799
U.S. government and agencies | Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	52	78
Foreign government | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	44	32
Foreign government | Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	44	32
Municipal | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	18	129
Municipal | Pension benefits | Significant unobservable inputs (Level 3)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	18	129
Total reported plan assets	18	129	163
Pension plan assets
Fair value of plan assets, beginning of year	129	163	222
Actual return on plan assets: Relating to assets sold during the period	7	5
Actual return on plan assets: Relating to assets still held at the reporting date	1	(2)	1
Purchases, sales and settlements, net	(119)	(37)	(60)
Fair value of plan assets, end of year	18	129	163
Corporate | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	1,451	1,004
Corporate | Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	1,433	994
Corporate | Pension benefits | Significant unobservable inputs (Level 3)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	18	10
Total reported plan assets	18	10	9
Pension plan assets
Fair value of plan assets, beginning of year	10	9	10
Actual return on plan assets: Relating to assets sold during the period	5	1	1
Purchases, sales and settlements, net	3		(2)
Fair value of plan assets, end of year	18	10	9
Residential mortgage-backed securities ("RMBS") | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	83	95
Residential mortgage-backed securities ("RMBS") | Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	83	95
Residential mortgage-backed securities ("RMBS") | Pension benefits | Significant unobservable inputs (Level 3)
Pension plan assets
Fair value of plan assets, beginning of year			48
Actual return on plan assets: Relating to assets sold during the period			(8)
Actual return on plan assets: Relating to assets still held at the reporting date			8
Purchases, sales and settlements, net			(30)
Net transfers in and/or (out) of Level 3			(18)
Limited partnership interests | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Target asset allocation, minimum range (as a percent)	12.00%
Target asset allocation, maximum range (as a percent)	18.00%
Actual percentage of plan assets	7.00%	9.00%
Short-term investments | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Cash collateral from target asset allocation, investment allocation (as a percent)	93.00%
Total plan assets at fair value	398	480
Short-term investments | Pension benefits | Quoted prices in active markets for identical assets (Level 1)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	54	56
Short-term investments | Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	344	424
Short-term investments and other | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Actual percentage of plan assets	3.00%	3.00%
Real estate funds | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	197	214
Real estate funds | Pension benefits | Significant unobservable inputs (Level 3)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	197	214
Total reported plan assets	197	214	192
Pension plan assets
Fair value of plan assets, beginning of year	214	192	167
Actual return on plan assets: Relating to assets sold during the period		16	(1)
Actual return on plan assets: Relating to assets still held at the reporting date	11	2	29
Purchases, sales and settlements, net	(28)	4	(3)
Fair value of plan assets, end of year	197	214	192
Private equity funds | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	211	199
Private equity funds | Pension benefits | Significant unobservable inputs (Level 3)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	211	199
Total reported plan assets	211	199	186
Pension plan assets
Fair value of plan assets, beginning of year	199	186	166
Actual return on plan assets: Relating to assets sold during the period		8	1
Actual return on plan assets: Relating to assets still held at the reporting date	(2)	(6)	22
Purchases, sales and settlements, net	14	11	(3)
Fair value of plan assets, end of year	211	199	186
Hedge funds | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	9	80
Hedge funds | Pension benefits | Significant unobservable inputs (Level 3)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	9	80
Total reported plan assets	9	80	79
Pension plan assets
Fair value of plan assets, beginning of year	80	79	120
Actual return on plan assets: Relating to assets sold during the period			43
Actual return on plan assets: Relating to assets still held at the reporting date		1	(43)
Purchases, sales and settlements, net	(71)		(41)
Fair value of plan assets, end of year	9	80	79
Cash and Cash Equivalents | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	25	17
Cash and Cash Equivalents | Pension benefits | Quoted prices in active markets for identical assets (Level 1)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	25	17
Free Standing Derivative Assets | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	4
Free Standing Derivative Assets | Pension benefits | Quoted prices in active markets for identical assets (Level 1)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	1
Free Standing Derivative Assets | Pension benefits | Significant other observable inputs (Level 2)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	3
Free Standing Derivatives Liabilities | Pension benefits
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	(1)
Free Standing Derivatives Liabilities | Pension benefits | Quoted prices in active markets for identical assets (Level 1)
Pension plans' weighted average target percentage of plan assets and the actual percentage of plan assets
Total plan assets at fair value	$ (1)