Commitments and Contingencies (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Long-term Purchase Commitment [Line Items]
Commitments	$ 34,613
Additions to property and equipment	20,043	$ 4,920
MMBTU Natual Gas Dollar Equivalent [Member]
Long-term Purchase Commitment [Line Items]
Commitments	8,375
Pounds Of Flour Dollar Equivalent [Member]
Long-term Purchase Commitment [Line Items]
Commitments	16,465
Capital Expenditures [Member]
Long-term Purchase Commitment [Line Items]
Aggregate purchase commitments	6,042
Purchases against purchase commitments	22,262
Remaining amount payable	$ (2,219)