IMPACT OF THE INVASION OF UKRAINE - (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2022	Jun. 30, 2021	Mar. 04, 2022	Dec. 31, 2021
Unusual or Infrequent Item, or Both [Line Items]
Property and equipment, net	$ 211,119,000		$ 211,119,000			$ 236,214,000
Operating lease, right-of-use asset	159,726,000		159,726,000			184,841,000
Commitments related to operating lease agreements that have not yet commenced	10,500,000		10,500,000
Impairment charges			21,002,000	$ 0
Goodwill impairment			686,000
Bad debt expense			11,748,000	$ 2,828,000
Humanitarian Commitment
Unusual or Infrequent Item, or Both [Line Items]
Nonoperating expense	8,400,000		34,000,000
Humanitarian Commitment | Cost of revenues (exclusive of depreciation and amortization)
Unusual or Infrequent Item, or Both [Line Items]
Nonoperating expense	3,300,000		22,400,000
Humanitarian Commitment | Selling, general and administrative expenses
Unusual or Infrequent Item, or Both [Line Items]
Nonoperating expense	5,100,000		11,600,000
Ukraine
Unusual or Infrequent Item, or Both [Line Items]
Property and equipment, net	70,901,000		70,901,000			78,289,000
Operating lease, right-of-use asset	14,400,000		14,400,000
Ukraine | Cost of revenues (exclusive of depreciation and amortization)
Unusual or Infrequent Item, or Both [Line Items]
Standby resources expense	9,300,000		11,800,000
Ukraine | Selling, general and administrative expenses
Unusual or Infrequent Item, or Both [Line Items]
Standby resources expense	14,400,000		33,100,000
Ukraine | Other income/(expense)
Unusual or Infrequent Item, or Both [Line Items]
Impairment charges		$ 1,300,000
Ukraine | Humanitarian Commitment
Unusual or Infrequent Item, or Both [Line Items]
Commitments related to operating lease agreements that have not yet commenced					$ 100,000,000
Russia
Unusual or Infrequent Item, or Both [Line Items]
Property and equipment, net	0		0			$ 16,611,000
Impairment of property, plant and equipment		15,100,000
Operating lease, impairment loss		3,800,000
Goodwill impairment		$ 700,000
Bad debt expense			8,200,000
Russia | Employee Severance
Unusual or Infrequent Item, or Both [Line Items]
Exit costs	16,200,000		16,200,000
Russia | Accrued compensation expenses | Employee Severance
Unusual or Infrequent Item, or Both [Line Items]
Exit costs			7,400,000
Building | Ukraine
Unusual or Infrequent Item, or Both [Line Items]
Property and equipment, net	70,900,000		70,900,000
Construction in Progress | Ukraine
Unusual or Infrequent Item, or Both [Line Items]
Property and equipment, net	50,700,000		50,700,000
Computer Equipment | Ukraine
Unusual or Infrequent Item, or Both [Line Items]
Property and equipment, net	12,500,000		12,500,000
Furniture and Fixtures | Ukraine
Unusual or Infrequent Item, or Both [Line Items]
Property and equipment, net	7,200,000		7,200,000
Leasehold Improvements | Ukraine
Unusual or Infrequent Item, or Both [Line Items]
Property and equipment, net	$ 500,000		$ 500,000