Derivative financial instruments and fair value measurements (Notional Amounts) (Details)	Jan. 02, 2016 bu lots
Corn [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	216,180
Soybean [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	399,985
Future And Forward Purchase Contracts [Member] | Corn [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	671,000
Future And Forward Purchase Contracts [Member] | Soybean [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	460,000
Future And Forward Sale Contracts [Member] | Corn [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(605,000)
Future And Forward Sale Contracts [Member] | Soybean [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(681,000)
Future [Member] | Corn [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(295,000)
Future [Member] | Soybean [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(210,000)
Not Designated as Hedging Instrument [Member] | Future And Forward Contracts [Member] | Cocoa [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount | lots	144