Employee Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 27, 2014 |
Dec. 28, 2013 |
Dec. 29, 2012 |
|
| Pension Benefits [Member] | |||
| Components of net periodic benefit cost: | |||
| Service cost | $ 75 | $ 295 | $ 276 |
| Interest cost | 1,081 | 963 | 1,055 |
| Amortization of loss | 117 | 387 | 261 |
| Expected return on plan assets | (1,378) | (1,348) | (1,300) |
| Net periodic benefit cost | (105) | 297 | 292 |
| Healthcare & Life Ins [Member] | |||
| Components of net periodic benefit cost: | |||
| Service cost | 106 | 236 | 207 |
| Interest cost | 493 | 513 | 585 |
| Amortization of loss | 227 | 314 | 312 |
| Expected return on plan assets | (180) | ||
| Curtailment benefit | (1,346) | ||
| Special termination benefits | 39 | ||
| Amortization of prior service credit | (174) | (180) | |
| Net periodic benefit cost | $ (694) | $ 922 | $ 924 |