GOODWILL AND INTANGIBLE ASSETS, NET - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 03, 2021	Jun. 27, 2020	Jul. 03, 2021	Jun. 27, 2020	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 320,993		$ 320,993		$ 320,993
Foreign Currency Translation			1,515		2,013
Accumulated Amortization	44,602		44,602		33,533
Net Amount	277,906		277,906		289,473
Amortization of Intangible Assets	5,479	$ 4,063	11,074	$ 8,126
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	135,100		135,100		135,100
Foreign Currency Translation			789		1,047
Accumulated Amortization	13,323		13,323		10,258
Net Amount	122,566		122,566		125,889
Patented technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	16,126		16,126		16,126
Foreign Currency Translation			117		155
Accumulated Amortization	4,335		4,335		3,452
Net Amount	11,908		11,908		12,829
Pool designs
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,728		5,728		5,728
Foreign Currency Translation			474		629
Accumulated Amortization	854		854		648
Net Amount	5,348		5,348		5,709
Franchise relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,187		1,187		1,187
Foreign Currency Translation			97		130
Accumulated Amortization	620		620		470
Net Amount	664		664		847
Dealer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	160,376		160,376		160,376
Foreign Currency Translation			39		52
Accumulated Amortization	24,212		24,212		17,697
Net Amount	136,203		136,203		142,731
Non-competition agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,476		2,476		2,476
Accumulated Amortization	1,258		1,258		1,008
Net Amount	$ 1,218		$ 1,218		$ 1,468