REVENUES - Contract Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Receivables	$ 703,199	$ 611,534
Contract assets (unbilled receivables)	69,912	55,681
Contract liabilities (deferred revenue)	$ 86,589	$ 74,066

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant