Employee Retirement Plans (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in Plan Assets:
Fair value as of December 31	$ 1,340	$ 1,262
Components on the Consolidated Balance Sheets:
Current liabilities	(22)	(14)
Noncurrent liabilities	(491)	(277)
Pension
Change in Benefit Obligation:
Benefit obligation as of January 1	1,376	1,536
Service cost	37	38	32
Interest cost	65	63	64
Curtailment/settlements	(24)	(103)
Participant contributions	10	10
Benefits paid	(81)	(38)
Plan amendment	0	1
Actuarial (gain) loss	327	(115)
Foreign currency translation	(24)	(16)
Benefit obligation as of December 31	1,686	1,376	1,536
Change in Plan Assets:
Fair value as of January 1	1,262	1,133
Actual return on plan assets	132	203
Employer contributions	64.0	71.0
Participant contributions	10	10
Benefits paid	(81)	(38)
Curtailment/settlements	(24)	(103)
Foreign currency translation	(23)	(14)
Fair value as of December 31	1,340	1,262	1,133
Funded status	(346)	(114)
Components on the Consolidated Balance Sheets:
Noncurrent assets	0	11
Current liabilities	(9)	(1)
Noncurrent liabilities	(337)	(124)
Net liability as of December 31	(346)	(114)
Pretax Components in AOCI:
Net actuarial loss	490	259
Prior service credit	(1)	0
Total as of December 31	489	259
Postretirement
Change in Benefit Obligation:
Benefit obligation as of January 1	166	186
Service cost	3	3	3
Interest cost	7	7	8
Curtailment/settlements	0	0
Participant contributions	8	8
Benefits paid	(20)	(21)
Plan amendment	4	0
Actuarial (gain) loss	4	(13)
Foreign currency translation	(5)	(4)
Benefit obligation as of December 31	167	166	186
Change in Plan Assets:
Fair value as of January 1	0	0
Actual return on plan assets	0	0
Employer contributions	12.0	13.0
Participant contributions	8	8
Benefits paid	(20)	(21)
Curtailment/settlements	0	0
Foreign currency translation	0	0
Fair value as of December 31	0	0	0
Funded status	(167)	(166)
Components on the Consolidated Balance Sheets:
Noncurrent assets	0	0
Current liabilities	(13)	(13)
Noncurrent liabilities	(154)	(153)
Net liability as of December 31	(167)	(166)
Pretax Components in AOCI:
Net actuarial loss	24	21
Prior service credit	(140)	(179)
Total as of December 31	$ (116)	$ (158)