GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Allocation of Acquisition Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Acquired Finite Lived Intangible Assets
Goodwill	$ 838,428	$ 840,117	$ 753,718
Amortizable intangibles, Gross carrying amount	623,428	616,051
Amortizable intangibles, Accumulated Amortization	292,239	237,137
Customer related intangibles
Acquired Finite Lived Intangible Assets
Amortizable intangibles, Gross carrying amount	$ 322,619	$ 321,019
Amortizable intangibles, Weighted Average Amortization Period	16 years	16 years
Amortizable intangibles, Accumulated Amortization	$ 116,609	$ 97,320
Acquired software
Acquired Finite Lived Intangible Assets
Amortizable intangibles, Gross carrying amount	$ 262,286	$ 262,286
Amortizable intangibles, Weighted Average Amortization Period	7 years	7 years
Amortizable intangibles, Accumulated Amortization	$ 162,378	$ 130,416
Trade names
Acquired Finite Lived Intangible Assets
Amortizable intangibles, Gross carrying amount	$ 22,905	$ 22,905
Amortizable intangibles, Weighted Average Amortization Period	11 years	11 years
Amortizable intangibles, Accumulated Amortization	$ 9,366	$ 7,205
Capitalized software development costs
Acquired Finite Lived Intangible Assets
Amortizable intangibles, Gross carrying amount	$ 10,581	$ 4,804
Amortizable intangibles, Weighted Average Amortization Period	5 years	5 years
Amortizable intangibles, Accumulated Amortization	$ 1,460	$ 296
Leases acquired
Acquired Finite Lived Intangible Assets
Amortizable intangibles, Gross carrying amount	$ 5,037	$ 5,037
Amortizable intangibles, Weighted Average Amortization Period	9 years	9 years
Amortizable intangibles, Accumulated Amortization	$ 2,426	$ 1,900