Restructuring and Impairment Charges - Charges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2019
Restructuring and impairment charges
Restructuring charges		$ 9			$ 13
Cost Smart cost of sales and SG&A Program
Restructuring and impairment charges
Restructuring charges	$ 11			$ 25
Cost Smart cost of sales and SG&A Program | Employee-related severance costs
Restructuring and impairment charges
Restructuring charges				3
Cost Smart Cost of Sales Program
Restructuring and impairment charges
Restructuring charges	6	3		15	4
Cost Smart Cost of Sales Program | Cessation of wet-milling
Restructuring and impairment charges
Restructuring charges		1			2
Cost Smart Cost of Sales Program, Production facility closure, Australia | Forecast
Restructuring and impairment charges
Restructuring charges			$ 2
Cost Smart Cost of Sales Program, Production facility closure, Australia | Asset write-off
Restructuring and impairment charges
Restructuring charges	3			6
Cost Smart Cost of Sales Program, Production facility closure, Australia | Accelerated depreciation
Restructuring and impairment charges
Restructuring charges				1
Cost Smart Cost of Sales Program, Production facility closure, Australia | Other restructuring costs
Restructuring and impairment charges
Restructuring charges	1			2
Cost Smart Cost of Sales Program, North America | Accelerated depreciation
Restructuring and impairment charges
Restructuring charges	1			4
Cost Smart Cost of Sales Program, North America | Employee-related severance costs
Restructuring and impairment charges
Restructuring charges	1			1
Cost Smart Cost of Sales Program, North America | Other restructuring costs
Restructuring and impairment charges
Restructuring charges				1
Cost Smart SG&A Program
Restructuring and impairment charges
Restructuring charges	5			10
Cost Smart SG&A Program | Employee-related severance costs
Restructuring and impairment charges
Restructuring charges				2
Cost Smart SG&A Program | Employee-related severance and other costs
Restructuring and impairment charges
Restructuring charges		6			9
Cost Smart SG&A Program | Other restructuring costs
Restructuring and impairment charges
Restructuring charges				$ 8
Cost Smart SG&A Program, Latin American Finance Transformation Initiative | Other restructuring costs
Restructuring and impairment charges
Restructuring charges		$ 1			$ 2
Cost Smart SG&A Program, North America
Restructuring and impairment charges
Restructuring charges	$ 5