Acquisition (Canyon Bakehouse LLC) - Additional Information (Detail) - Canyon Bakehouse LLC - USD ($) $ in Thousands		12 Months Ended
	Dec. 14, 2018	Dec. 29, 2018
Business Acquisition [Line Items]
Percentage of outstanding membership interests acquired	100.00%
Date of acquisition		Dec. 14, 2018
Business acquisition, description		On December 14, 2018, the company completed the acquisition of 100% of the outstanding membership interests of Canyon, a leading gluten-free bread baker, from its members for total consideration of $205.2 million, including a $5.0 million earn-out recorded as contingent consideration.  We believe the acquisition of Canyon strengthens our position as the second-largest baker in the U.S. by giving us access to the fast-growing gluten-free bread category. The acquisition has been accounted for as a business combination. Canyon’s sales and results of operations were immaterial for fiscal 2018.  The total goodwill recorded for this acquisition was $80.5 million and it is deductible for tax purposes.
Total consideration paid	$ 205,222
Business acquisition, earn-out contingent consideration	5,000
Goodwill acquired	$ 80,500
Acquisition-related costs		$ 4,500
Fair value of trade receivable		3,600
Gross amount receivables		3,700
Uncollectible receivables amount		$ 100