Employee Benefit Plans (Details 6) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Measurements of Company's Pension Plans
Investment in company's common stock	$ 12	$ 9
U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	9,550	10,274	$ 11,090
U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	3,297	3,306
U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	4,824	5,422
U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,429	1,546
International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	4,174	4,109	$ 4,244
International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,548	1,196
International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	2,274	2,508
International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	352	405
U.S equity [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,217	1,699
U.S equity [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,217	1,699
U.S equity [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
U.S equity [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
U.S equity [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	565	392
U.S equity [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	564	382
U.S equity [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1	10
U.S equity [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
International Equity Securities [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,832	1,302
International Equity Securities [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,822	1,296
International Equity Securities [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	10	6
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	576	457
International Equity Securities [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	576	435
International Equity Securities [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	22
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	1,132	2,460
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	24	18
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	1,108	2,442
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	0
Collective Trusts Mutual Funds Equity [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	196	572
Collective Trusts Mutual Funds Equity [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	8	7
Collective Trusts Mutual Funds Equity [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	188	565
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	0
Government [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	222	257
Government [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	46
Government [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	222	211
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	1,125	1,089
Government [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	51	93
Government [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,074	996
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	1,356	1,654
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	1,356	1,654
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	628	615
Corporate [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	22	33
Corporate [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	587	557
Corporate [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	19	25
Bank Loans [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	118	148
Bank Loans [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Bank Loans [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	107	148
Bank Loans [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	11	0
Bank Loans [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Bank Loans [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Bank Loans [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Bank Loans [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Mortgage-Backed Securities [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1	1
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	1	1
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	10	1
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	10	1
Mortgage-Backed Securities [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Other Asset Backed [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	1
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	0	1
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	0	0
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	0	0
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	1,031	933
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	0
Collective Trusts/Mutual Funds [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,031	933
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	0
Collective Trusts/Mutual Funds [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	320	269
Collective Trusts/Mutual Funds [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	12
Collective Trusts/Mutual Funds [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	320	257
Collective Trusts/Mutual Funds [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Mixed Funds [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Mixed Funds [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Mixed Funds [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Mixed Funds [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Mixed Funds [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	72	85
Mixed Funds [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	2	4
Mixed Funds [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	70	81
Mixed Funds [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Real Estate [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,367	1,494
Real Estate [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Real Estate [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Real Estate [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	1,367	1,494
Real Estate [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	331	378
Real Estate [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Real Estate [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	0
Real Estate [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	331	378
Alternative Investments [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	955
Alternative Investments [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0
Alternative Investments [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	955
Alternative Investments [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0
Alternative Investments [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0
Alternative Investments [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0
Alternative Investments [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0
Alternative Investments [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0
Cash And Cash Equivalents [Member] | U.S. [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	252	253
Cash And Cash Equivalents [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	243	253
Cash And Cash Equivalents [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	9	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	331	232
Cash And Cash Equivalents [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	325	232
Cash And Cash Equivalents [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	6	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	67	72
Other [Member] | U.S. [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	(9)	(6)
Other [Member] | U.S. [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	25	26
Other [Member] | U.S. [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	51	52
Other [Member] | International [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	20	19
Other [Member] | International [Member] | Level 1 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	0	(2)
Other [Member] | International [Member] | Level 2 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	18	19
Other [Member] | International [Member] | Level 3 [Member]
Fair Value Measurements of Company's Pension Plans
Fair value of plan assets	$ 2	$ 2