Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 741	$ 1,470	$ 1,133	$ 8,629
Effective income tax expense (benefit) rate	16.20%	27.60%	16.00%	33.10%
Excess tax benefit	$ 300		$ 600
Decrease in effective tax rate	7.20%		8.10%
Gain on divestitures	$ 0	$ 0	$ 0	$ 18,815
Unrecognized tax benefits	3,400		3,400		$ 3,000
Expected reduction in unrecognized tax benefits	$ 2,200		$ 2,200