Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 25, 2017	Jun. 30, 2018	Jun. 25, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory rate			21.00%		35.00%
Additional expense on re-measurement of deferred tax assets			$ 1,600
Income tax expense (benefit)	$ 4,795	$ (1,722)	$ 8,165	$ (1,524)
Effective income tax rate	37.10%	18.60%	30.70%	25.60%