ACQUISITIONS ASSETS ACQUIRED (TABLES) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Nov. 04, 2020	Aug. 05, 2020	Feb. 07, 2020	Dec. 31, 2019	Oct. 26, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Operating lease assets	$ 120,820				$ 150,808
Deferred tax assets.	57,332				60,392
Goodwill	363,502				301,694		$ 204,633
Operating lease liability - short-term	43,651				45,218
Accrued employee compensation and benefits	163,658				114,165
Operating lease liability - long-term	$ 98,277				$ 127,395
Voice Foundry US
Business Acquisition [Line Items]
Accounts receivable.			$ 3,758
Prepaid Expenses			345
Goodwill			35,891
Total assets acquired			47,094
Accounts payable			289
Accrued employee compensation and benefits			741
Deferred revenue.			170
Total liabilities assumed			1,200
Total purchase price			45,894
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
FCR
Business Acquisition [Line Items]
Cash						$ 5,225
Accounts receivable.						10,659
Prepaid Expenses						357
Property, plant and equipment.						6,006
Other assets						224
Operating lease assets						5,127
Goodwill						96,739
Total assets acquired						171,477
Accounts payable						388
Operating lease liability - short-term						1,160
Accrued employee compensation and benefits						4,049
Accrued expenses						72
Operating lease liability - long-term						3,967
Total liabilities assumed						9,636
Total purchase price						161,841
FCR | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets						8,600
FCR | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets						$ 38,540