Fair Value Measurements - Liabilities at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 28, 2018	Dec. 29, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Non-controlling interest subject to put provisions	$ 14,852	$ 12,955
Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Credit facility	59,397	63,058
Non-controlling interest subject to put provisions	14,852	12,955
Total liabilities measured at fair value	74,249	76,013
Recurring | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Credit facility	0	0
Non-controlling interest subject to put provisions	0	0
Total liabilities measured at fair value	0	0
Recurring | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Credit facility	59,397	63,058
Non-controlling interest subject to put provisions	0	0
Total liabilities measured at fair value	59,397	63,058
Recurring | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Credit facility	0	0
Non-controlling interest subject to put provisions	14,852	12,955
Total liabilities measured at fair value	$ 14,852	$ 12,955