XML 81 R56.htm IDEA: XBRL DOCUMENT v3.20.4
Business, Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details)
$ in Millions
12 Months Ended
Dec. 31, 2020
USD ($)
Segment
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]      
Number of segments | Segment 5    
Property, Plant and Equipment [Line Items]      
Cost basis of property, equipment and leasehold improvements $ 2,800 $ 2,700  
Accumulated depreciation and amortization of property, equipment and leasehold improvements 1,500 1,400  
Depreciation and amortization expense $ 194 207 $ 191
Minimum      
Real Estate Held-for-investment And Accumulated Depreciation [Line Items]      
Real Estate Held-for-investment And Accumulated Depreciation Life Used For Depreciation 20 years    
Maximum      
Real Estate Held-for-investment And Accumulated Depreciation [Line Items]      
Real Estate Held-for-investment And Accumulated Depreciation Life Used For Depreciation 55 years    
Building      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Useful Life 40 years    
Leasehold Improvements | Minimum      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Useful Life 1 year    
Leasehold Improvements | Maximum      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Useful Life 25 years    
Other Capitalized Property Plant and Equipment | Minimum      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Useful Life 3 years    
Other Capitalized Property Plant and Equipment | Maximum      
Property, Plant and Equipment [Line Items]      
Property, Plant and Equipment, Useful Life 7 years    
VODA and VOCRA | Minimum      
Finite-Lived Intangible Assets [Line Items]      
Amortization period 9 years    
VODA and VOCRA | Maximum      
Finite-Lived Intangible Assets [Line Items]      
Amortization period 40 years    
Computer Software, Intangible Asset      
Finite-Lived Intangible Assets [Line Items]      
Amortization period 4 years    
Cost basis of computer software $ 3,700 3,400  
Accumulated amortization of computer software 2,500 2,500  
Amortization expense related to computer software $ 207 $ 262 $ 276