Net Income per Share - Computation of Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 27, 2021	Mar. 28, 2020
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Earnings to Common Shareholders, As reported - basic		$ 65,565	$ 18,234
Weighted-average number of common shares — basic		12,271	12,157
EPS, As reported - basic		$ 5.34	$ 1.50
Add: effect of dilutive potential common shares Share-based awards		162	116
Earnings to Common Shareholders, Net effect of unvested participating shares		$ 299	$ 1
Common Shares, Net effect of unvested participating shares		80
Earnings to Common Shareholders, Net income per common share — diluted		$ 65,565	$ 18,104
Common Shares, Net income per common share — diluted		12,457	12,186
EPS, Net income per common share — diluted		$ 5.26	$ 1.49
Common Class A
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Earnings to Common Shareholders, As reported - basic		$ 53,628	$ 14,136
Weighted-average number of common shares — basic		10,037	9,425
EPS, As reported - basic		$ 5.34	$ 1.50
Common Class B
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Earnings to Common Shareholders, As reported - basic		$ 11,638	$ 3,967
Weighted-average number of common shares — basic	[1]	2,178	2,645
EPS, As reported - basic		$ 5.34	$ 1.50
Earnings to Common Shareholders, Class B Common Stock		$ 11,638	$ 3,967
Class B Common Stock		2,178	2,645

[1] Change in Class B Common Stock resulted from the conversion of 215,000 shares to Class A Common Stock on May 6, 2020 and 130,000 shares to Class A Common Stock on November 3, 2020 with the ending number of shares reflecting the weighted average for the period.