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Fair value portion of assets, excluding financial assets, that lack physical substance, having a limited useful life.

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FAIR VALUE MEASUREMENT - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019	Dec. 29, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment loss	$ (140,489)
Impairment of finite-lived intangible assets	(34,700)
Goodwill and intangible asset impairment charge	(175,189)	$ 0
Fair value, nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment loss	(140,489)
Impairment of finite-lived intangible assets	(34,700)
Goodwill and intangible asset impairment charge	(175,189)
Fair value, nonrecurring [Member] \| Quoted prices in active markets for identical assets (level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	0
Client relationships	0
Total	0
Fair value, nonrecurring [Member] \| Significant other observable inputs (level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	0
Client relationships	0
Total	0
Fair value, nonrecurring [Member] \| Significant unobservable inputs (level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	93,290
Client relationships	27,108
Total	120,398
Fair value, nonrecurring [Member] \| Total fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	93,290
Client relationships	27,108
Total	$ 120,398		$ 295,600