Computation of Diluted Net Income Per Share (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands |
3 Months Ended |
6 Months Ended |
Jun. 25, 2016 |
Jun. 27, 2015 |
Jun. 25, 2016 |
Jun. 27, 2015 |
| Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] |
|
|
|
|
| Allocation of net income for basic common stock |
$ 26,621
|
$ 29,932
|
$ 33,653
|
$ 43,675
|
| Weighted-average number of common shares-diluted |
12,830
|
13,667
|
12,959
|
13,650
|
| Net income per common share-basic |
$ 2.11
|
$ 2.24
|
$ 2.65
|
$ 3.28
|
| Net income per common share-diluted |
$ 2.06
|
$ 2.18
|
$ 2.58
|
$ 3.18
|
| Common Class A |
|
|
|
|
| Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] |
|
|
|
|
| Allocation of net income for basic common stock |
$ 19,375
|
$ 21,870
|
$ 24,567
|
$ 31,740
|
| Allocation of net income to Class B Common Stock |
7,107
|
7,923
|
8,916
|
11,729
|
| Net effect of unvested participating shares |
3
|
4
|
4
|
6
|
| Net Income for diluted common stock |
$ 26,485
|
$ 29,797
|
$ 33,487
|
$ 43,475
|
| Weighted-average number of common shares-basic |
9,181
|
9,748
|
9,278
|
9,673
|
| Add: effect of dilutive potential common share-based awards |
282
|
387
|
314
|
402
|
| Weighted average number of shares of Class B Common Stock |
3,367
|
3,532
|
3,367
|
3,575
|
| Weighted-average number of common shares-diluted |
12,830
|
13,667
|
12,959
|
13,650
|
| Net income per common share-basic |
$ 2.11
|
$ 2.24
|
$ 2.65
|
$ 3.28
|
| Net income per common share-diluted |
$ 2.06
|
$ 2.18
|
$ 2.58
|
$ 3.18
|