REVENUES (Schedule of Disaggregation of Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 1,167,527	$ 1,152,136	$ 3,479,589	$ 3,533,283
Revenues from performance obligations satisfied in previous period	1,600	9,200	15,000	7,100
Transferred over time
Disaggregation of Revenue [Line Items]
Revenues	1,162,937	1,149,241	3,465,406	3,522,805
Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues	4,590	2,895	14,183	10,478
Time-and-material
Disaggregation of Revenue [Line Items]
Revenues	968,167	995,599	2,893,314	3,098,598
Fixed-price
Disaggregation of Revenue [Line Items]
Revenues	191,515	147,056	563,490	412,914
Licensing and other revenues
Disaggregation of Revenue [Line Items]
Revenues	7,845	9,481	22,785	21,771
Consumer Goods, Retail & Travel
Disaggregation of Revenue [Line Items]
Revenues	251,125	262,957	762,582	814,776
Financial Services
Disaggregation of Revenue [Line Items]
Revenues	254,635	246,435	741,740	776,068
Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues	178,073	174,346	520,327	538,755
Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues	167,394	183,861	503,474	575,925
Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues	142,334	124,244	422,627	349,943
Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues	173,966	160,293	528,839	477,816
Americas
Disaggregation of Revenue [Line Items]
Revenues	697,167	677,410	2,081,286	2,066,299
EMEA
Disaggregation of Revenue [Line Items]
Revenues	444,867	446,237	1,325,435	1,369,259
APAC
Disaggregation of Revenue [Line Items]
Revenues	25,493	25,051	72,868	76,080
CEE
Disaggregation of Revenue [Line Items]
Revenues	0	3,438	0	21,645
North America
Disaggregation of Revenue [Line Items]
Revenues	704,613	684,778	2,107,971	2,074,806
North America | Transferred over time
Disaggregation of Revenue [Line Items]
Revenues	701,014	682,410	2,097,251	2,066,081
North America | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues	3,599	2,368	10,720	8,725
North America | Time-and-material
Disaggregation of Revenue [Line Items]
Revenues	596,111	602,765	1,793,852	1,854,159
North America | Fixed-price
Disaggregation of Revenue [Line Items]
Revenues	102,239	73,640	296,602	202,144
North America | Licensing and other revenues
Disaggregation of Revenue [Line Items]
Revenues	6,263	8,373	17,517	18,503
North America | Consumer Goods, Retail & Travel
Disaggregation of Revenue [Line Items]
Revenues	107,866	115,778	339,556	359,475
North America | Financial Services
Disaggregation of Revenue [Line Items]
Revenues	129,339	131,499	377,000	410,527
North America | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues	131,145	136,520	392,600	422,073
North America | Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues	115,121	104,863	332,602	327,378
North America | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues	120,659	109,137	362,983	305,700
North America | Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues	100,483	86,981	303,230	249,653
North America | Americas
Disaggregation of Revenue [Line Items]
Revenues	669,582	654,717	2,002,942	1,991,871
North America | EMEA
Disaggregation of Revenue [Line Items]
Revenues	34,679	29,251	103,220	80,252
North America | APAC
Disaggregation of Revenue [Line Items]
Revenues	352	786	1,809	2,161
North America | CEE
Disaggregation of Revenue [Line Items]
Revenues	0	24	0	522
Europe
Disaggregation of Revenue [Line Items]
Revenues	462,914	465,813	1,371,618	1,442,402
Europe | Transferred over time
Disaggregation of Revenue [Line Items]
Revenues	461,923	465,286	1,368,155	1,440,682
Europe | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues	991	527	3,463	1,720
Europe | Time-and-material
Disaggregation of Revenue [Line Items]
Revenues	372,056	391,479	1,099,462	1,233,271
Europe | Fixed-price
Disaggregation of Revenue [Line Items]
Revenues	89,276	73,226	266,888	205,897
Europe | Licensing and other revenues
Disaggregation of Revenue [Line Items]
Revenues	1,582	1,108	5,268	3,234
Europe | Consumer Goods, Retail & Travel
Disaggregation of Revenue [Line Items]
Revenues	143,259	146,837	423,026	451,531
Europe | Financial Services
Disaggregation of Revenue [Line Items]
Revenues	125,296	114,122	364,740	358,091
Europe | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues	46,928	37,545	127,727	115,137
Europe | Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues	52,273	78,983	170,872	248,351
Europe | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues	21,675	15,143	59,644	44,123
Europe | Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues	73,483	73,183	225,609	225,169
Europe | Americas
Disaggregation of Revenue [Line Items]
Revenues	27,585	22,693	78,344	73,797
Europe | EMEA
Disaggregation of Revenue [Line Items]
Revenues	410,188	416,986	1,222,215	1,289,007
Europe | APAC
Disaggregation of Revenue [Line Items]
Revenues	25,141	24,265	71,059	73,919
Europe | CEE
Disaggregation of Revenue [Line Items]
Revenues	0	1,869	0	5,679
Russia
Disaggregation of Revenue [Line Items]
Revenues	$ 0	1,545	$ 0	16,075
Russia | Transferred over time
Disaggregation of Revenue [Line Items]
Revenues		1,545		16,042
Russia | Transferred at a point of time
Disaggregation of Revenue [Line Items]
Revenues		0		33
Russia | Time-and-material
Disaggregation of Revenue [Line Items]
Revenues		1,355		11,168
Russia | Fixed-price
Disaggregation of Revenue [Line Items]
Revenues		190		4,873
Russia | Licensing and other revenues
Disaggregation of Revenue [Line Items]
Revenues		0		34
Russia | Consumer Goods, Retail & Travel
Disaggregation of Revenue [Line Items]
Revenues		342		3,770
Russia | Financial Services
Disaggregation of Revenue [Line Items]
Revenues		814		7,450
Russia | Software & Hi-Tech
Disaggregation of Revenue [Line Items]
Revenues		281		1,545
Russia | Business Information & Media
Disaggregation of Revenue [Line Items]
Revenues		15		196
Russia | Life Sciences & Healthcare
Disaggregation of Revenue [Line Items]
Revenues		(36)		120
Russia | Emerging Verticals
Disaggregation of Revenue [Line Items]
Revenues		129		2,994
Russia | Americas
Disaggregation of Revenue [Line Items]
Revenues		0		631
Russia | EMEA
Disaggregation of Revenue [Line Items]
Revenues		0		0
Russia | APAC
Disaggregation of Revenue [Line Items]
Revenues		0		0
Russia | CEE
Disaggregation of Revenue [Line Items]
Revenues		$ 1,545		$ 15,444