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Business, Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2022 USD ($) Segment | Dec. 31, 2021 USD ($) | Dec. 31, 2020 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 | $ 2,500 | $ 2,700 |
Accumulated depreciation and amortization of property, equipment and leasehold improvements | 1,600 | 1,600 |
Depreciation and amortization expense | 171 | 192 | $ 194
Finite-Lived Intangible Assets [Line Items] |  |  |
Operating Lease, Right-of-Use Asset, Amortization Expense | $ 3 | 45 | 0
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 | Maximum |  |  |
Property, Plant and Equipment [Line Items] |  |  |
Property, Plant and Equipment, Useful Life | 10 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 | $ 4,400 | 4,000 |
Accumulated amortization of computer software | 2,800 | 2,700 |
Amortization expense related to computer software | $ 252 | $ 234 | $ 207

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