GOODWILL AND INTANGIBLE ASSETS - Intangible Assets, Net by Major Class (Details) - USD ($) $ in Thousands	Dec. 28, 2019	Dec. 29, 2018
Finite-lived intangible assets
Gross	$ 1,112,348	$ 939,910
Accumulated Amortization	(422,935)	(329,022)
Net	689,413	610,888
Backlog
Finite-lived intangible assets
Gross	28,865	20,900
Accumulated Amortization	(26,895)	(18,691)
Net	1,970	2,209
Technology
Finite-lived intangible assets
Gross	122,106	101,506
Accumulated Amortization	(57,737)	(41,870)
Net	64,369	59,636
Trademarks and trade names
Finite-lived intangible assets
Gross	8,430	8,331
Accumulated Amortization	(4,901)	(4,640)
Net	3,529	3,691
Other
Finite-lived intangible assets
Gross	18,279	17,448
Accumulated Amortization	(12,307)	(10,041)
Net	5,972	7,407
Other intangible assets
Finite-lived intangible assets
Gross	177,680	148,185
Accumulated Amortization	(101,840)	(75,242)
Net	75,840	72,943
Client relationships
Finite-lived intangible assets
Gross	934,668	791,725
Accumulated Amortization	(321,095)	(253,780)
Net	$ 613,573	$ 537,945