Restructuring and Related Implementation Charges - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) employees	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Total Global Growth and Efficiency Program charges, pretax	$ 88	$ 152	$ 93
Global Growth and Efficiency Program
Restructuring Cost and Reserve [Line Items]
Expected percent of total charges resulting in cash expenditure	80.00%
Pretax charges related to the Restructuring Program to date	$ 1,722
Restructuring and related cost incurred cost to date after tax	1,278
Charges against assets	(27)	(40)	(33)
Total Global Growth and Efficiency Program charges, pretax	$ 161	333	228
Global Growth and Efficiency Program | Pet Nutrition
Restructuring Cost and Reserve [Line Items]
Expected percent of total restructuring charges related to segment for the duration of the program	10.00%
Global Growth and Efficiency Program | Corporate
Restructuring Cost and Reserve [Line Items]
Expected percent of total restructuring charges related to segment for the duration of the program	40.00%
Global Growth and Efficiency Program | North America
Restructuring Cost and Reserve [Line Items]
Expected percent of total restructuring charges related to segment for the duration of the program	15.00%
Global Growth and Efficiency Program | Europe
Restructuring Cost and Reserve [Line Items]
Expected percent of total restructuring charges related to segment for the duration of the program	20.00%
Global Growth and Efficiency Program | Latin America
Restructuring Cost and Reserve [Line Items]
Expected percent of total restructuring charges related to segment for the duration of the program	5.00%
Global Growth and Efficiency Program | Asia Pacific
Restructuring Cost and Reserve [Line Items]
Expected percent of total restructuring charges related to segment for the duration of the program	5.00%
Global Growth and Efficiency Program | Africa/Eurasia
Restructuring Cost and Reserve [Line Items]
Expected percent of total restructuring charges related to segment for the duration of the program	5.00%
Global Growth and Efficiency Program | Employee-Related Costs
Restructuring Cost and Reserve [Line Items]
Estimated percent of total cumulative pretax charges of implementing restructuring program by category	45.00%
Pretax charges related to the Restructuring Program to date	$ 681
Charges against assets	(9)	(21)	(4)
Total Global Growth and Efficiency Program charges, pretax	$ 53	163	61
Global Growth and Efficiency Program | Incremental Depreciation And Asset Impairment
Restructuring Cost and Reserve [Line Items]
Estimated percent of total cumulative pretax charges of implementing restructuring program by category	5.00%
Global Growth and Efficiency Program | Charges Resulting Directly From Exit Activities
Restructuring Cost and Reserve [Line Items]
Estimated percent of total cumulative pretax charges of implementing restructuring program by category	30.00%
Global Growth and Efficiency Program | Implementation Of New Strategies
Restructuring Cost and Reserve [Line Items]
Estimated percent of total cumulative pretax charges of implementing restructuring program by category	20.00%
Global Growth and Efficiency Program | Third party Incremental Cost
Restructuring Cost and Reserve [Line Items]
Total Global Growth and Efficiency Program charges, pretax	$ 42	145	116
Global Growth and Efficiency Program | Contract Termination
Restructuring Cost and Reserve [Line Items]
Total Global Growth and Efficiency Program charges, pretax	48	6	21
Global Growth and Efficiency Program | Land and Building
Restructuring Cost and Reserve [Line Items]
Total Global Growth and Efficiency Program charges, pretax	0	$ 0	$ 1
Global Growth and Efficiency Program | Minimum | Expected Completion Date 2019
Restructuring Cost and Reserve [Line Items]
Restructuring program expected cost before tax	1,820
Restructuring program total expected cost after tax	1,350
Restructuring program expected cost, upcoming fiscal year, before tax	100
Restructuring program expected cost, upcoming fiscal year, after tax	$ 70
Restructuring and related cost, expected number of positions eliminated (in positions) | employees	4,000
Global Growth and Efficiency Program | Maximum | Expected Completion Date 2019
Restructuring Cost and Reserve [Line Items]
Restructuring program expected cost before tax	$ 1,870
Restructuring program total expected cost after tax	1,380
Restructuring program expected cost, upcoming fiscal year, before tax	150
Restructuring program expected cost, upcoming fiscal year, after tax	$ 100
Restructuring and related cost, expected number of positions eliminated (in positions) | employees	4,400