Employee Benefit Plans - Effects of One Percentage-Point Change in Assumed Health Care Cost Trend Rates (Detail) - USD ($) $ in Thousands |
12 Months Ended | |
---|---|---|
Jan. 02, 2016 |
Dec. 27, 2014 |
|
Compensation and Retirement Disclosure [Abstract] | ||
Total service cost and interest cost components, Increase | $ 45 | $ 39 |
APBO, Increase | 1,302 | 1,333 |
Total service cost and interest cost components, Decrease | (36) | (34) |
APBO, Decrease | (1,121) | (1,136) |
Summit Materials, LLC [Member] | ||
Compensation and Retirement Disclosure [Abstract] | ||
Total service cost and interest cost components, Increase | 45 | 39 |
APBO, Increase | 1,302 | 1,333 |
Total service cost and interest cost components, Decrease | (36) | (34) |
APBO, Decrease | $ (1,121) | $ (1,136) |