Computation of Earnings Per Share, Basic (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended									12 Months Ended
		Dec. 31, 2016	[1]	Sep. 24, 2016	Jun. 25, 2016	Mar. 26, 2016	Dec. 26, 2015	Sep. 26, 2015	Jun. 27, 2015	Mar. 28, 2015	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income		$ 22,166		$ 31,530	$ 26,621	$ 7,032	$ 16,115	$ 38,624	$ 29,932	$ 13,743	$ 87,349	$ 98,414	$ 90,743
Allocation of net income for basic:
Allocation of net income for basic common stock											87,349	98,414	90,743
Allocation of net income for basic unvested participating shares											$ 442	$ 462	$ 509
Weighted average number of shares for basic:
Weighted average number of shares for basic unvested participating shares											64	62	73
Shares used in net income per common share - basic											12,597	13,185	13,041
Net income per share for basic:
Net income per common share - basic		$ 1.77		$ 2.53	$ 2.11	$ 0.55	$ 1.25	$ 2.93	$ 2.24	$ 1.04	$ 6.93	$ 7.46	$ 6.96
Common Class A
Allocation of net income for basic:
Allocation of net income for basic common stock											$ 63,717	$ 71,798	$ 64,027
Weighted average number of shares for basic:
Weighted-average number of common shares - basic											9,189	9,619	9,202
Net income per share for basic:
Net income per common share - basic											$ 6.93	$ 7.46	$ 6.96
Common Class B
Allocation of net income for basic:
Allocation of net income for basic common stock											$ 23,190	$ 26,154	$ 26,207
Weighted average number of shares for basic:
Weighted-average number of common shares - basic	[2]										3,344	3,504	3,766
Net income per share for basic:
Net income per common share - basic											$ 6.93	$ 7.46	$ 6.96

[1] 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.

[2] Change in Class B Common Stock resulted from the conversion of 150,000 shares to Class A Common Stock on May 6, 2015, 100,000 shares to Class A Common Stock on October 26, 2015, 125,000 shares to Class A Common Stock on November 4, 2016 and 45,000 shares to Class A Common Stock on November 30, 2016, with the ending number of shares reflecting the weighted average for the period.