Segment Reporting - Revenues and Income from Operations for Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Revenues
Revenue from Contract with Customer, Including Assessed Tax	$ 243,839	$ 218,955	$ 697,588	$ 631,994
Segment income (loss) from operations
Total income from operations	6,906	13,984	29,394	35,586
UNITED STATES
Revenues
Revenue from Contract with Customer, Including Assessed Tax	204,450	179,705	581,238	520,557
Segment income (loss) from operations
Total income from operations	8,101	12,352	30,452	31,739
CANADA
Revenues
Revenue from Contract with Customer, Including Assessed Tax	37,422	37,430	110,574	106,292
Segment income (loss) from operations
Total income from operations	(1,514)	1,480	(1,671)	3,140
Other Segments [Member]
Revenues
Revenue from Contract with Customer, Including Assessed Tax	1,967	1,820	5,776	5,145
Segment income (loss) from operations
Total income from operations	$ 319	$ 152	$ 613	$ 707