Commitments and Contingencies Sales Return Liability (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016
Sales return liability [Roll Forward]
Balance at beginning of year	$ 15,222	$ 20,562
Additions that reduce net sales	55,720	54,588
Deductions from reserves	(52,494)	(57,112)
Balance at end of period	$ 18,448	$ 18,038