Annual report pursuant to Section 13 and 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)

v3.22.0.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)
shares in Millions
 12 Months Ended
Dec. 31, 2021
USD ($)
segment
shares
Dec. 31, 2020
USD ($)
shares
Dec. 31, 2019
USD ($)
shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Number of reportable segments | segment 3    
Number of operating segments | segment 3    
Contract assets $ 12,100,000    
Advertising costs from continuing operations 70,200,000 $ 59,000,000 $ 51,900,000
Depreciation and amortization 489,600,000 399,300,000 337,300,000
Fixed assets, pledged as collateral 156,400,000 156,400,000  
Goodwill and intangible asset impairment 0 0 0
Carrying value of investment 56,400,000 127,700,000  
Unrealized loss on investment 64,000,000    
Unrealized gain on investment   116,600,000  
Foreign currency transaction loss 2,600,000 7,500,000 3,000,000
Fair value of debt 5,200,000,000 4,800,000,000  
Long term debt carrying amount 5,000,000,000 4,400,000,000  
Variable interest entity, maximum exposure to loss 30,200,000    
Redemption premium 0    
Property and Equipment      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Depreciation and amortization $ 304,000,000 249,300,000 $ 191,000,000
Minimum | Computer Software Intangible Asset      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Property, plant and equipment useful life 3 years    
Maximum | Computer Software Intangible Asset      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Property, plant and equipment useful life 10 years    
Data Processing Equipment Capitalized Internal Use Software and Systems Costs | Minimum      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Property, plant and equipment useful life 3 years    
Data Processing Equipment Capitalized Internal Use Software and Systems Costs | Maximum      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Property, plant and equipment useful life 10 years    
Building      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Property, plant and equipment useful life 40 years    
Other Capitalized Property Plant and Equipment | Minimum      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Property, plant and equipment useful life 3 years    
Other Capitalized Property Plant and Equipment | Maximum      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Property, plant and equipment useful life 7 years    
Other Current Assets      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Income taxes receivable, current $ 18,100,000 21,300,000  
Restricted cash 28,500,000 25,100,000  
Other Current Liabilities      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Restricted cash 28,500,000 25,100,000  
Legal fees $ 373,600,000 $ 379,700,000  
Stock Options      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Antidilutive stock options excluded from computation of earnings per share (in shares) | shares 0.0 0.4 1.1
Total Workforce Solutions | Revenue Benchmark | Segment Concentration Risk      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Largest segment's percent of total operating revenue (as a percent) 42.00%    
Cybersecurity Incident | Other Current Liabilities      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Legal fees $ 350,700,000 $ 355,200,000  
Other Income      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Foreign currency transaction gain $ 800,000    
Foreign currency transaction loss   $ 500,000 $ 1,000,000