Share-based Compensation (Details) $ in Thousands	3 Months Ended		6 Months Ended		18 Months Ended
	Jun. 28, 2016 USD ($) shares	Jun. 30, 2015 USD ($)	Jun. 28, 2016 USD ($) shares	Jun. 30, 2015 USD ($)	Jun. 28, 2016 item shares
Share-based compensation expenses
Share-based compensation expense	$ 5,915	$ 5,311	$ 11,703	$ 10,215
Number of executives granted performance stock units | item					2
Number of common shares that a holder would receive upon satisfaction of the vesting requirement (in shares) | shares	1		1		1
Number of common shares that a holder would receive upon meeting a performance obligation and vesting requirement (in shares) | shares	1		1		1
Labor expense
Share-based compensation expenses
Share-based compensation expense	$ 1,507	1,035	$ 2,906	2,550
General and administrative expense
Share-based compensation expenses
Share-based compensation expense	$ 4,408	$ 4,276	$ 8,797	$ 7,665