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Organization and Significant Accounting Policies - Narrative (Details)
12 Months Ended
Dec. 31, 2021
USD ($)
segment
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]      
Number of operating segments | segment 1    
Number of reportable segments | segment 1    
Debt security credit losses $ 0 $ 0  
Impairment charges on debt securities     $ 0
Sales commissions amortization period 3 years    
Impairment charges $ 0 0 0
Interest and penalties $ 0 $ 0 $ 0