Employee Retirement Plans - Projected Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in Plan Assets:
Fair value as of beginning of period	$ 1,301
Fair value as of end of period	1,435	$ 1,301
Components on the Consolidated Balance Sheets:
Current liabilities	(24)	(18)
Noncurrent liabilities	(290)	(392)
Pension
Change in Benefit Obligation:
Benefit obligation as of beginning of period	1,564	1,686
Service cost	45	49	$ 37
Interest cost	66	66	65
Settlements	(123)	(4)
Curtailments	(37)	0
Participant contributions	11	11
Benefits paid	(33)	(86)
Actuarial (gain) loss	112	(119)
Foreign currency translation	5	(39)
Benefit obligation as of end of period	1,610	1,564	1,686
Change in Plan Assets:
Fair value as of beginning of period	1,301	1,340
Actual return on plan assets	107	17
Employer contributions	167	61
Participant contributions	11	11
Benefits paid	(33)	(86)
Settlements	(123)	(4)
Foreign currency translation	5	(38)
Fair value as of end of period	1,435	1,301	1,340
Funded status	(175)	(263)
Components on the Consolidated Balance Sheets:
Noncurrent assets	4	3
Current liabilities	(16)	(9)
Noncurrent liabilities	(163)	(257)
Net liability as of December 31	(175)	(263)
Pretax Components in AOCI:
Net actuarial loss	388	387
Prior service credit	(1)	(1)
Total as of end of year	387	386
Postretirement
Change in Benefit Obligation:
Benefit obligation as of beginning of period	144	167
Service cost	2	2	3
Interest cost	6	6	7
Settlements	0	0
Curtailments	(7)	0
Participant contributions	0	3
Benefits paid	(7)	(11)
Actuarial (gain) loss	(5)	(14)
Foreign currency translation	2	(9)
Benefit obligation as of end of period	135	144	167
Change in Plan Assets:
Fair value as of beginning of period	0	0
Actual return on plan assets	0	0
Employer contributions	7	8
Participant contributions	0	3
Benefits paid	(7)	(11)
Settlements	0	0
Foreign currency translation	0	0
Fair value as of end of period	0	0	$ 0
Funded status	(135)	(144)
Components on the Consolidated Balance Sheets:
Noncurrent assets	0	0
Current liabilities	(8)	(9)
Noncurrent liabilities	(127)	(135)
Net liability as of December 31	(135)	(144)
Pretax Components in AOCI:
Net actuarial loss	0	7
Prior service credit	(65)	(108)
Total as of end of year	$ (65)	$ (101)