ACQUISITIONS ASSETS ACQUIRED (TABLES) (Details) - USD ($) $ in Thousands	Apr. 08, 2021	Jun. 30, 2021	Dec. 31, 2020	Nov. 04, 2020	Aug. 05, 2020	Feb. 07, 2020
Business Acquisition [Line Items]
Operating lease assets		$ 106,735	$ 120,820
Goodwill		733,940	363,502
Operating lease liability - short-term		42,891	43,651
Accrued employee compensation and benefits		156,585	163,658
Operating lease liability - long-term		$ 83,146	$ 98,277
Avtex
Business Acquisition [Line Items]
Cash	$ 18,638
Accounts receivable.	25,342
Prepaid Expenses	30,541
Other assets	468
Operating lease assets	3,210
Income Taxes Receivable	93
Fixed Assets Acquired	3,162
Goodwill	370,883
Total assets acquired	582,167
Accounts payable	22,563
Operating lease liability - short-term	543
Accrued employee compensation and benefits	4,325
Accrued income taxes	332
Accrued expenses	250
Operating lease liability - long-term	2,667
Deferred revenue.	51,542
Total liabilities assumed	82,222
Total purchase price	499,945
Avtex | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets	5,300
Avtex | Intellectual Property [Member]
Business Acquisition [Line Items]
Intangible assets	770
Avtex | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets	$ 123,760
Voice Foundry US
Business Acquisition [Line Items]
Accounts receivable.					$ 3,758
Prepaid Expenses					345
Goodwill					35,881
Total assets acquired					47,084
Accounts payable					289
Accrued employee compensation and benefits					741
Deferred revenue.					170
Total liabilities assumed					1,200
Total purchase price					45,884
Voice Foundry US | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets					400
Voice Foundry US | Noncompete Agreements [Member]
Business Acquisition [Line Items]
Intangible assets					150
Voice Foundry US | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets					$ 6,550
Voice Foundry ASEAN
Business Acquisition [Line Items]
Cash				$ 1,300
Accounts receivable.				937
Prepaid Expenses				115
Property, plant and equipment.				274
Income Taxes Receivable				30
Goodwill				14,418
Total assets acquired				20,474
Accounts payable				960
Accrued employee compensation and benefits				113
Deferred tax liabilities				1,013
Deferred revenue.				236
Other accrued assets liabilities, net				(78)
Total liabilities assumed				2,244
Total purchase price				18,230
Voice Foundry ASEAN | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets				300
Voice Foundry ASEAN | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets				$ 3,100
Serendebyte
Business Acquisition [Line Items]
Cash						$ 3,123
Accounts receivable.						1,243
Prepaid Expenses						1,327
Property, plant and equipment.						20
Deferred tax assets.						14
Goodwill						9,033
Total assets acquired						17,080
Accounts payable						120
Accrued employee compensation and benefits						1,025
Accrued income taxes						170
Accrued expenses						2,208
Deferred tax liabilities						629
Total liabilities assumed						4,152
Total purchase price						12,928
Serendebyte | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets						400
Serendebyte | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets						$ 1,920