Schedule of Fair Value Assets Measured on Recurring Basis (Details) - Fair value, measurements, recurring - USD ($) $ in Thousands		Jun. 28, 2015	Dec. 28, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		$ 26,318	$ 29,425
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		1,013	874
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		25,305	28,551
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets		0	0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds (1)	[1]	26,318	29,425
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds (1)	[1]	1,013	874
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds (1)	[1]	25,305	28,551
Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds (1)	[1]	$ 0	$ 0

[1] Money market funds are presented as a part of cash and cash equivalents on the accompanying consolidated balance sheets as of June 28, 2015 and December 28, 2014.