Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Recurring - USD ($) $ in Thousands	Sep. 29, 2018	Sep. 30, 2017
Liabilities:
Total liabilities	$ 8,224	$ 9,343
Liability for Contingent Consideration
Liabilities:
Total liabilities	8,224	9,343
Level 1
Liabilities:
Total liabilities	0	0
Level 1 | Liability for Contingent Consideration
Liabilities:
Total liabilities	0	0
Level 2
Liabilities:
Total liabilities	0	0
Level 2 | Liability for Contingent Consideration
Liabilities:
Total liabilities	0	0
Level 3
Liabilities:
Total liabilities	8,224	9,343
Level 3 | Liability for Contingent Consideration
Liabilities:
Total liabilities	$ 8,224	$ 9,343