Postretirement Benefit Plans (Pension Plan Investments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure
Investments	$ 43,981	$ 48,510
Pension Benefit Plan [Member]
Defined Benefit Plan Disclosure
Private Equities	6,269	6,878
Real estate	3,354	3,356
Other investments	1,791	1,738
Investments	48,469	45,379
Cash and other	(172)	(641)
Total assets	48,297	44,738
Pension Benefit Plan [Member] | Fixed Income And Cash Investment Funds [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	2,078	1,981
Pension Benefit Plan [Member] | Domestic Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	4,555	2,758
Pension Benefit Plan [Member] | Residential Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	1,093	1,423
Pension Benefit Plan [Member] | US Government Agencies Debt Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	5,253	5,489
Pension Benefit Plan [Member] | Other Debt Obligations [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	2,317	2,075
Pension Benefit Plan [Member] | US Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	12,635	11,338
Pension Benefit Plan [Member] | Non US Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	9,124	8,343
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure
Private Equities	0	0
Real estate	0	0
Other investments	0	0
Investments	18,899	15,575
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed Income And Cash Investment Funds [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	0
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Domestic Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	0
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Residential Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	0
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	0
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Other Debt Obligations [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	0
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | US Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	11,067	8,876
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Non US Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	7,832	6,699
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure
Private Equities	0	0
Real estate	0	0
Other investments	169	44
Investments	18,325	17,801
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Income And Cash Investment Funds [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	2,078	1,931
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Domestic Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	4,555	2,758
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Residential Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	1,093	1,420
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	5,253	5,489
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Other Debt Obligations [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	2,317	2,053
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | US Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	1,568	2,462
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Non US Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	1,292	1,644
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure
Private Equities	6,269	6,878
Real estate	3,354	3,356
Other investments	1,622	1,694
Investments	11,245	12,003
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Income And Cash Investment Funds [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	50
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Domestic Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	0
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Residential Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	3
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	0
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Other Debt Obligations [Member]
Defined Benefit Plan Disclosure
Trading Securities, Debt	0	22
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | US Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	0	0
Pension Benefit Plan [Member] | Fair Value, Inputs, Level 3 [Member] | Non US Equity Securities [Member]
Defined Benefit Plan Disclosure
Equity securities	$ 0	$ 0