Employee Benefit Plans (Details 6) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Fair Value Measurements of Company's Pension Plans
Investment in company's common stock	$ 27		$ 35
U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	9,909		8,720		8,579
U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	3,704		3,168
U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	5,036		4,655
U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,169		897
International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	4,125		3,577		3,503
International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,552		1,542
International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	2,362		1,849
International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	211		186
U.S equity [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,709	[1]	1,470	[1]
U.S equity [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,709	[1]	1,470	[1]
U.S equity [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[1]	0	[1]
U.S equity [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[1]	0	[1]
U.S equity [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	334	[1]	497	[1]
U.S equity [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	334	[1]	497	[1]
U.S equity [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[1]	0	[1]
U.S equity [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[1]	0	[1]
International Equity Securities [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,263		1,203
International Equity Securities [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,263		1,203
International Equity Securities [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
International Equity Securities [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
International Equity Securities [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	520		693
International Equity Securities [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	520		693
International Equity Securities [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
International Equity Securities [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Collective Trusts Mutual Funds Equity [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	2,979	[2]	2,633	[2]
Collective Trusts Mutual Funds Equity [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	7	[2]	14	[2]
Collective Trusts Mutual Funds Equity [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	2,972	[2]	2,619	[2]
Collective Trusts Mutual Funds Equity [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[2]	0	[2]
Collective Trusts Mutual Funds Equity [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,233	[2]	596	[2]
Collective Trusts Mutual Funds Equity [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	402	[2]	28	[2]
Collective Trusts Mutual Funds Equity [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	831	[2]	568	[2]
Collective Trusts Mutual Funds Equity [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[2]	0	[2]
Government [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	435		622
Government [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	396		146
Government [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	39		476
Government [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Government [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	578		635
Government [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	40		25
Government [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	538		610
Government [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Corporate [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	384		338
Corporate [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Corporate [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	384		338
Corporate [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Corporate [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	230		319
Corporate [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	25		16
Corporate [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	175		276
Corporate [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	30		27
Mortgage-Backed Securities [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	65		107
Mortgage-Backed Securities [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Mortgage-Backed Securities [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	65		107
Mortgage-Backed Securities [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Mortgage-Backed Securities [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	2		2
Mortgage-Backed Securities [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Mortgage-Backed Securities [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Mortgage-Backed Securities [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	2		2
Other Asset Backed [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	51		61
Other Asset Backed [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Other Asset Backed [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	51		61
Other Asset Backed [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Other Asset Backed [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	4		5
Other Asset Backed [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Other Asset Backed [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	4		5
Other Asset Backed [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Collective Trusts/Mutual Funds [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,520	[2]	1,046	[2]
Collective Trusts/Mutual Funds [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[2]	0	[2]
Collective Trusts/Mutual Funds [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,520	[2]	1,046	[2]
Collective Trusts/Mutual Funds [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[2]	0	[2]
Collective Trusts/Mutual Funds [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	671	[2]	345	[2]
Collective Trusts/Mutual Funds [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	26	[2]	61	[2]
Collective Trusts/Mutual Funds [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	645	[2]	284	[2]
Collective Trusts/Mutual Funds [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[2]	0	[2]
Mixed Funds [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[3]	10	[3]
Mixed Funds [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[3]	10	[3]
Mixed Funds [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[3]	0	[3]
Mixed Funds [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[3]	0	[3]
Mixed Funds [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	115	[3]	102	[3]
Mixed Funds [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	4	[3]	13	[3]
Mixed Funds [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	111	[3]	89	[3]
Mixed Funds [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[3]	0	[3]
Real Estate [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,114	[4]	843	[4]
Real Estate [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[4]	0	[4]
Real Estate [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[4]	0	[4]
Real Estate [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,114	[4]	843	[4]
Real Estate [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	177	[4]	155	[4]
Real Estate [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[4]	0	[4]
Real Estate [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	[4]	0	[4]
Real Estate [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	177	[4]	155	[4]
Cash And Cash Equivalents [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	373		404
Cash And Cash Equivalents [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	373		404
Cash And Cash Equivalents [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Cash And Cash Equivalents [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Cash And Cash Equivalents [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	222		211
Cash And Cash Equivalents [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	204		211
Cash And Cash Equivalents [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	18		0
Cash And Cash Equivalents [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0		0
Other [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	16	[5]	(17)	[5]
Other [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	(44)	[5]	(79)	[5]
Other [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	5	[5]	8	[5]
Other [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	55	[5]	54	[5]
Other [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	39	[5]	17	[5]
Other [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	(3)	[5]	(2)	[5]
Other [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	40	[5]	17	[5]
Other [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	$ 2	[5]	$ 2	[5]

[1] U.S. equities include investments in the company’s common stock in the amount of $27 at December 31, 2012, and $35 at December 31, 2011.

[2] Collective Trusts/Mutual Funds for U.S. plans are entirely index funds; for International plans, they are mostly index funds. For these index funds, the Level 2 designation is partially based on the restriction that advance notification of redemptions, typically two business days, is required.

[3] Mixed funds are composed of funds that invest in both equity and fixed-income instruments in order to diversify and lower risk.

[4] The year-end valuations of the U.S. real estate assets are based on internal appraisals by the real estate managers, which are updates of third-party appraisals that occur at least once a year for each property in the portfolio.

[5] The “Other” asset class includes net payables for securities purchased but not yet settled (Level 1); dividends and interest- and tax-related receivables (Level 2); insurance contracts and investments in private-equity limited partnerships (Level 3).