Operating Results reported as discontinued operations (Details) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Jul. 03, 2015	Dec. 31, 2014	Sep. 26, 2014	Jun. 27, 2014	Mar. 28, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Discontinued Operations And Disposal Groups [Abstract]
Revenue from discontinued operations							$ 10,514	$ 33,792
Loss from discontinued operations, before income tax						$ (13)	(8,059)	(3,361)
Loss from discontinued operations, net of tax	$ (13)	$ (790)	$ (273)	$ (2,678)	$ (1,866)	$ (13)	(5,607)	(2,054)
Loss on disposal of discontinued operations, net of tax		$ (1,405)	$ (321)				$ (1,726)	$ (592)