Related-Party Transactions - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2015 USD ($) Stockholders	Jun. 29, 2014 USD ($)	Jun. 28, 2015 USD ($)	Jun. 29, 2014 USD ($)
Coffee Supplier [Member]
Related Party Transaction [Line Items]
Purchases from investors	$ 2.5	$ 1.8	$ 4.8	$ 3.8
Accounts payable to vendor	$ 0.7	0.7	0.7	0.7
Number of stockholders that are investors in a company that is a supplier of coffee to the Company | Stockholders	2
Technology Supplier [Member]
Related Party Transaction [Line Items]
Purchases from investors	$ 1.8	2.0	3.1	2.9
Accounts payable to vendor	$ 0.2	$ 0.3	$ 0.2	$ 0.3
Number of senior executive purchased stock in a technology supplier to the Company | Stockholders	1