v3.26.3
Fair Value of Financial Instruments - Narrative (Details)
$ in Millions
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2026
USD ($)
tranche
Sep. 30, 2025
USD ($)
Sep. 30, 2026
USD ($)
tranche
Sep. 30, 2025
USD ($)
Dec. 31, 2022
USD ($)
Aug. 31, 2026
tranche
shares
Aug. 14, 2026
USD ($)
Feb. 28, 2026
shares
Dec. 31, 2025
USD ($)
Sep. 01, 2025
tranche
shares
Oct. 31, 2021
USD ($)
tranche
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Number of tranches expired | tranche                   3  
Warrants $ 14   $ 14           $ 58    
Interest rate swap | Cash Flow Hedging                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Fixed interest rate             4.055%        
Derivative, notional amount 1,660   1,660       $ 1,660        
Derivative, quarterly amortization             4        
Derivative, notional amount after amortization             $ 1,635        
Estimated net gain in AOCI expected to be reclassified into interest expense, net, in the next 12 months, pre-tax $ 7   $ 7                
Root Warrants                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Equity securities, not readily determinable fair value                     $ 126
Number of tranches | tranche 5   5               8
Number of tranches expired | tranche                   3  
Number of securities called by warrants (in shares) | shares           7,200,000          
Number of tranches cancelled | tranche           5          
Number of tranches exercisable | tranche           2          
Loss on derecognition of warrant derivative asset $ 11                    
Root Warrants | Warrants                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Deferred revenue 39   $ 39           36    
Deferred revenue recognized $ 5 $ 5 $ 16 $ 16              
Root Warrants for 2.4 million shares                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Number of securities called by warrants (in shares) | shares                   2,400,000  
Root Warrants for 3.2 million shares                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Number of securities called by warrants (in shares) | shares                   3,200,000  
Root Warrants for 1.6 million shares                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Number of securities called by warrants (in shares) | shares                   1,600,000  
Root Warrants for 1.4 million shares                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Number of securities called by warrants (in shares) | shares                   1,400,000  
Root Warrants for 1.5 million shares                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Number of securities called by warrants (in shares) | shares               1,500,000      
New Root Warrants                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Number of tranches | tranche           5          
Number of securities called by warrants (in shares) | shares           1,500,000          
Warrants and rights outstanding, term           2 years          
New Root Warrants, Per Tranche                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Number of securities called by warrants (in shares) | shares           305,112          
Measurement Input, Price Volatility | Root Warrants                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Warrants and rights outstanding, measurement input 0.85 1 0.85 1              
Level 3                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Warrants $ 14   $ 14           $ 58    
Level 3 | Root Warrants                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Warrants 30   30                
Level 3 | Root Warrants | Warrants                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
New Root Warrants to acquire Root's Class A common stock 19 $ 0 19 $ 0 $ 75            
Total increase (decrease) in fair value (5) (120) (50) 3              
Variable Interest Entity, Not Primary Beneficiary | Level 3 | Fair Value, Measurements, Recurring                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Proceeds from sale of beneficial interests $ 0 $ 0 $ 29 $ 0              
Variable Interest Entity, Not Primary Beneficiary | Level 3 | Fair Value, Measurements, Recurring | Measurement Input, Weighted Average Discount Rate | Valuation Technique, Discounted Cash Flow                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Measurement input, discount rate 0.092   0.092           0.09    
Minimum | Variable Interest Entity, Not Primary Beneficiary | Level 3 | Fair Value, Measurements, Recurring | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Measurement input, discount rate 0.057   0.057           0.052    
Maximum | Variable Interest Entity, Not Primary Beneficiary | Level 3 | Fair Value, Measurements, Recurring | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow                      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]                      
Measurement input, discount rate 0.10   0.10           0.10