Computation of Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended										12 Months Ended
		Dec. 30, 2017	[1]	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	[2]	Sep. 24, 2016	Jun. 25, 2016	Mar. 26, 2016	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Allocation of net income for basic common stock												$ 99,049	$ 87,349	$ 98,414
Earnings to Common Shareholders, Net effect of unvested participating shares												7	9	14
Earnings to Common Shareholders, Net income per common share - diluted												$ 98,512	$ 86,916	$ 97,966
Add: effect of dilutive potential common shares Share-based awards												145	263	397
Weighted-average number of common shares - diluted												12,180	12,796	13,520
Net income per common share-basic		$ 2.60		$ 2.82	$ 2.38	$ 0.46	$ 1.77		$ 2.53	$ 2.11	$ 0.55	$ 8.18	$ 6.93	$ 7.46
Net income per common share-diluted		$ 2.57		$ 2.78	$ 2.35	$ 0.45	$ 1.75		$ 2.48	$ 2.06	$ 0.53	$ 8.09	$ 6.79	$ 7.25
Common Class A
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Allocation of net income for basic common stock												$ 73,114	$ 63,717	$ 71,798
Weighted-average number of common shares - basic												8,933	9,189	9,619
Net income per common share-basic												$ 8.18	$ 6.93	$ 7.46
Common Class B
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Allocation of net income for basic common stock												$ 25,391	$ 23,190	$ 26,154
Earnings to Common Shareholders, Class B Common Stock												$ 25,391	$ 23,190	$ 26,154
Weighted-average number of common shares - basic	[3]											3,102	3,344	3,504
Add: effect of dilutive potential common shares, Class B Common Stock												3,102	3,344	3,504
Net income per common share-basic												$ 8.18	$ 6.93	$ 7.46

[1] During the fourth quarter of 2017, the Company recorded a $20.3 million tax benefit due to the Tax Cuts and Jobs Act of 2017.

[2] During the fourth quarter of 2016, the Company recorded a $3.6 million decrease in stock-based compensation expense related to the planned retirement of the Company's Chief Executive Officer in 2018.

[3] Change in Class B Common Stock resulted from the conversion of 125,000 shares to Class A Common Stock on November 4, 2016, 45,000 shares to Class A Common Stock on November 30, 2016, 100,000 shares to Class A Common Stock on March 7, 2017, and 79,000 shares to Class A Common Stock on October 31, 2017 with the ending number of shares reflecting the weighted average for the period.