Fixed Assets, Net - Components of Fixed Assets, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 679,489	$ 621,806
Less: accumulated depreciation and amortization	(486,910)	(431,794)
Fixed assets, net	192,579	190,012
Computer and communications equipment
Property, Plant and Equipment [Line Items]
Fixed assets, gross	122,549	112,463
Software, including software development costs
Property, Plant and Equipment [Line Items]
Fixed assets, gross	432,634	401,040
Leasehold improvements and other fixed assets
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 124,306	$ 108,303

Amount of accumulated depreciation and amortization from plant, property, and equipment and right-of-use asset from finance lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount, after accumulated depreciation and amortization, of property, plant, and equipment and finance lease right-of-use asset.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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-Publisher FASB
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Amount, before accumulated depreciation and amortization, of property, plant, and equipment and finance lease right-of-use asset.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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