Commitments and Contingencies (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Long-term Purchase Commitment [Line Items]
Commitments	$ 37,237
MMBTU Natual Gas Dollar Equivalent [Member]
Long-term Purchase Commitment [Line Items]
Commitments	12,190
Pounds Of Flour Dollar Equivalent [Member]
Long-term Purchase Commitment [Line Items]
Commitments	10,193
Dryers [Member]
Long-term Purchase Commitment [Line Items]
Commitments	5,489
Purchases made against commitment	3,849
Capital Expenditures [Member]
Long-term Purchase Commitment [Line Items]
Aggregate purchase commitments	$ 2,890