Pension and Other Postretirement Benefits - Pension Plan Assets (Details) (Pension Benefits [Member], USD $) In Millions, unless otherwise specified													12 Months Ended																																												12 Months Ended																												12 Months Ended								12 Months Ended									12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Fair Value Inputs Level 3 [Member]	Dec. 31, 2011 Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Company Subsidiaries [Member]	Dec. 31, 2013 Buyer Of Retirement Benefits Business [Member]	Dec. 31, 2013 Fixed Maturities [Member]	Dec. 31, 2012 Fixed Maturities [Member]	Dec. 31, 2013 Fixed Maturities [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Fixed Maturities [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Fixed Maturities [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Fixed Maturities [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Fixed Maturities [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Fixed Maturities [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Federal government and agency [Member]	Dec. 31, 2012 Federal government and agency [Member]	Dec. 31, 2013 Federal government and agency [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Federal government and agency [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Federal government and agency [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Federal government and agency [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Federal government and agency [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Federal government and agency [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Corporate [Member]	Dec. 31, 2012 Corporate [Member]	Dec. 31, 2013 Corporate [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Corporate [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Corporate [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Corporate [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Corporate [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Corporate [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Other asset and mortgage-backed securities [Member]	Dec. 31, 2012 Other asset and mortgage-backed securities [Member]	Dec. 31, 2013 Other asset and mortgage-backed securities [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Other asset and mortgage-backed securities [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Other asset and mortgage-backed securities [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Other asset and mortgage-backed securities [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Other asset and mortgage-backed securities [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Other asset and mortgage-backed securities [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Fund Investments And Pooled Separate Accounts [Member]	Dec. 31, 2012 Fund Investments And Pooled Separate Accounts [Member]		Dec. 31, 2013 Fund Investments And Pooled Separate Accounts [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Fund Investments And Pooled Separate Accounts [Member] Fair Value Inputs Level 1 [Member]		Dec. 31, 2013 Fund Investments And Pooled Separate Accounts [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Fund Investments And Pooled Separate Accounts [Member] Fair Value Inputs Level 2 [Member]		Dec. 31, 2013 Fund Investments And Pooled Separate Accounts [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Fund Investments And Pooled Separate Accounts [Member] Fair Value Inputs Level 3 [Member]		Dec. 31, 2013 Equity securities [Member]	Dec. 31, 2012 Equity securities [Member]	Dec. 31, 2013 Equity securities [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Equity securities [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Equity securities [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Equity securities [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Equity securities [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Equity securities [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Domestic [Member]	Dec. 31, 2012 Domestic [Member]	Dec. 31, 2013 Domestic [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Domestic [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Domestic [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Domestic [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Domestic [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Domestic [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 International, including funds and pooled seperate accounts [Member]		Dec. 31, 2012 International, including funds and pooled seperate accounts [Member]	Dec. 31, 2013 International, including funds and pooled seperate accounts [Member] Fair Value Inputs Level 1 [Member]		Dec. 31, 2012 International, including funds and pooled seperate accounts [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 International, including funds and pooled seperate accounts [Member] Fair Value Inputs Level 2 [Member]		Dec. 31, 2012 International, including funds and pooled seperate accounts [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 International, including funds and pooled seperate accounts [Member] Fair Value Inputs Level 3 [Member]		Dec. 31, 2012 International, including funds and pooled seperate accounts [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Real Estate [Member]	Dec. 31, 2012 Real Estate [Member]	Dec. 31, 2013 Real Estate [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Real Estate [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Real Estate [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Real Estate [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Real Estate [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Real Estate [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Securities Partnerships [Member]	Dec. 31, 2012 Securities Partnerships [Member]	Dec. 31, 2013 Securities Partnerships [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Securities Partnerships [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Securities Partnerships [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Securities Partnerships [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Securities Partnerships [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Securities Partnerships [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2011 Securities Partnerships [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Hedge Funds [Member]	Dec. 31, 2012 Hedge Funds [Member]	Dec. 31, 2013 Hedge Funds [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Hedge Funds [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Hedge Funds [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Hedge Funds [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Hedge Funds [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Hedge Funds [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2011 Hedge Funds [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Guaranteed Deposit Account Contract [Member]	Dec. 31, 2012 Guaranteed Deposit Account Contract [Member]	Dec. 31, 2013 Guaranteed Deposit Account Contract [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Guaranteed Deposit Account Contract [Member] Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Guaranteed Deposit Account Contract [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Guaranteed Deposit Account Contract [Member] Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Guaranteed Deposit Account Contract [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Guaranteed Deposit Account Contract [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2011 Guaranteed Deposit Account Contract [Member] Fair Value Inputs Level 3 [Member]	Dec. 31, 2013 Cash equivalents	Dec. 31, 2012 Cash equivalents	Dec. 31, 2013 Cash equivalents Fair Value Inputs Level 1 [Member]	Dec. 31, 2012 Cash equivalents Fair Value Inputs Level 1 [Member]	Dec. 31, 2013 Cash equivalents Fair Value Inputs Level 2 [Member]	Dec. 31, 2012 Cash equivalents Fair Value Inputs Level 2 [Member]	Dec. 31, 2013 Cash equivalents Fair Value Inputs Level 3 [Member]	Dec. 31, 2012 Cash equivalents Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 4,089	$ 3,665	$ 3,298	$ 1,011	$ 1,360	$ 1,957	$ 1,207	$ 1,121	$ 1,098	$ 830	$ 3,800	$ 245	$ 1,796	$ 982	$ 0	$ 0	$ 1,764	$ 947	$ 32	$ 35	$ 2	$ 4	$ 0	$ 0	$ 2	$ 4	$ 0	$ 0	$ 749	$ 443	$ 0	$ 0	$ 725	$ 416	$ 24	$ 27	$ 23	$ 13	$ 0	$ 0	$ 18	$ 8	$ 5	$ 5	$ 1,022	$ 522	[1]	$ 0	$ 0	[1]	$ 1,019	$ 519	[1]	$ 3	$ 3	[1]	$ 1,177	$ 1,523	$ 1,011	$ 1,360	$ 124	$ 153	$ 42	$ 10	$ 859	$ 1,216	$ 824	$ 1,202	$ 0	$ 4	$ 35	$ 10	$ 318	[1]	$ 307	$ 187	[1]	$ 158	$ 124	[1]	$ 149	$ 7	[1]	$ 0	$ 339	$ 351	$ 0	$ 0	$ 0	$ 0	$ 339	$ 351	$ 304	$ 328	$ 0	$ 0	$ 0	$ 0	$ 304	$ 328	$ 314	$ 360	$ 327	$ 0	$ 0	$ 0	$ 0	$ 360	$ 327	$ 148	$ 44	$ 47	$ 0	$ 0	$ 0	$ 0	$ 44	$ 47	$ 39	$ 69	$ 107	$ 0	$ 0	$ 69	$ 107	$ 0	$ 0
Target allocation percentages													50.00%																																												25.00%																												7.00%								11.00%									7.00%
Actual allocation percentages																																																									29.00%

[1] A pooled separate account has several participating benefit plans and each owns a share of the total pool of investments.