v3.26.3
Fair Value Measurements - Carrying Amount and Estimated Fair Values of Company's Financial Instruments (Detail) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Assets    
Net finance receivables, less unearned insurance premiums and allowance for credit losses $ 1,930,052 $ 1,866,403
Restricted AFS investments 24,015 24,211
Level 1 [Member] | Carrying Amount [Member]    
Assets    
Cash 7,628 3,823
Restricted cash 133,276 94,174
Level 1 [Member] | Estimated Fair Value [Member]    
Assets    
Cash 7,628 3,823
Restricted cash 133,276 94,174
Level 3 [Member] | Carrying Amount [Member]    
Assets    
Net finance receivables, less unearned insurance premiums and allowance for credit losses 1,930,052 1,866,403
Liabilities:    
Debt 1,749,991 1,650,764
Level 3 [Member] | Estimated Fair Value [Member]    
Assets    
Net finance receivables, less unearned insurance premiums and allowance for credit losses 1,958,987 1,893,834
Liabilities:    
Debt 1,721,003 1,636,727
Level 2 [Member] | Carrying Amount [Member] | Fair Value, Recurring    
Assets    
Restricted AFS investments 24,015 24,211
Level 2 [Member] | Estimated Fair Value [Member] | Fair Value, Recurring    
Assets    
Restricted AFS investments $ 24,015 $ 24,211