Income Tax Expense (Benefit) Differs from Amount that would Result from Applying Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 29, 2020	Dec. 31, 2019	Jan. 01, 2019
Income Tax Disclosure [Abstract]
Income tax at statutory rates	(21.00%)	21.00%	21.00%
State income taxes, net of federal benefit	(5.20%)	3.00%	3.30%
Permanent differences	0.30%	(0.60%)	(5.10%)
Income tax credits	(5.10%)	(20.10%)	(16.00%)
Prior year tax credit true-up	(0.40%)	(0.70%)	(0.80%)
Benefit from net operating loss carryback	(5.20%)
Other, net	1.00%	(0.30%)	(0.10%)
Effective Income Tax Rate, Continuing Operations, Total	(35.60%)	2.30%	2.30%