BUSINESS COMBINATIONS AND DIVESTITURE - Definite Lived Intangible Assets (Details) - USD ($) $ in Thousands	Apr. 29, 2019	Apr. 03, 2018	Aug. 04, 2017
Citoxlab
Business Acquisition [Line Items]
Definite-Lived Intangible Assets	$ 162,400
Weighted Average Amortization Life	12 years
MPI Research
Business Acquisition [Line Items]
Definite-Lived Intangible Assets		$ 309,200
Weighted Average Amortization Life		12 years
Brains On-Line
Business Acquisition [Line Items]
Definite-Lived Intangible Assets			$ 9,300
Weighted Average Amortization Life			12 years
Client relationships | Citoxlab
Business Acquisition [Line Items]
Definite-Lived Intangible Assets	$ 134,600
Weighted Average Amortization Life	13 years
Client relationships | MPI Research
Business Acquisition [Line Items]
Definite-Lived Intangible Assets		$ 264,900
Weighted Average Amortization Life		13 years
Client relationships | Brains On-Line
Business Acquisition [Line Items]
Definite-Lived Intangible Assets			$ 7,000
Weighted Average Amortization Life			13 years
Developed technology | Citoxlab
Business Acquisition [Line Items]
Definite-Lived Intangible Assets	$ 19,900
Weighted Average Amortization Life	3 years
Developed technology | MPI Research
Business Acquisition [Line Items]
Definite-Lived Intangible Assets		$ 23,400
Weighted Average Amortization Life		3 years
Developed technology | Brains On-Line
Business Acquisition [Line Items]
Definite-Lived Intangible Assets			$ 2,300
Weighted Average Amortization Life			10 years
Backlog | Citoxlab
Business Acquisition [Line Items]
Definite-Lived Intangible Assets	$ 7,900
Weighted Average Amortization Life	1 year
Backlog | MPI Research
Business Acquisition [Line Items]
Definite-Lived Intangible Assets		$ 20,900
Weighted Average Amortization Life		1 year