Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Restructuring and asset impairment charges
Restructuring charge		$ 10
Restructuring accrual
Balance in severance accrual at December 31, 2015	$ 10
Payments made to terminated employees	(2)
Balance in severance accrual at March 31, 2016	$ 8
Penford
Restructuring accrual
Restructuring charge for employee severance costs		$ 10