ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES - Balance sheet (Details) - USD ($) $ in Thousands	Jun. 27, 2020	Dec. 28, 2019
Condensed Balance Sheet Statements, Captions [Line Items]
Prepaid expenses and other current assets	$ 15,279	$ 19,644
Operating lease right-of-use assets	34,963	37,768
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accrued expenses and other current liabilities	42,003	42,088
Current operating lease liabilities	8,086	7,768
Noncurrent operating lease liabilities	38,589	$ 42,200
No. 2016-02
Condensed Balance Sheet Statements, Captions [Line Items]
Prepaid expenses and other current assets	18,473
Operating lease right-of-use assets	34,588
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accrued expenses and other current liabilities	43,699
Current operating lease liabilities	5,599
Noncurrent operating lease liabilities	41,517
Other liabilities	4,119
As Previously Reported | No. 2016-02
Condensed Balance Sheet Statements, Captions [Line Items]
Prepaid expenses and other current assets	17,762
Operating lease right-of-use assets	0
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accrued expenses and other current liabilities	44,575
Current operating lease liabilities	0
Noncurrent operating lease liabilities	0
Other liabilities	15,060
Impact of Adoption | No. 2016-02
Condensed Balance Sheet Statements, Captions [Line Items]
Prepaid expenses and other current assets	711
Operating lease right-of-use assets	34,588
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accrued expenses and other current liabilities	(876)
Current operating lease liabilities	5,599
Noncurrent operating lease liabilities	41,517
Other liabilities	$ (10,941)